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* [PATCH v10 4/7] Row pattern recognition patch (executor).
@ 2023-10-22 02:22 Tatsuo Ishii <[email protected]>
0 siblings, 0 replies; 8+ messages in thread
From: Tatsuo Ishii @ 2023-10-22 02:22 UTC (permalink / raw)
---
src/backend/executor/nodeWindowAgg.c | 1363 +++++++++++++++++++++++++-
src/backend/utils/adt/windowfuncs.c | 37 +-
src/include/catalog/pg_proc.dat | 6 +
src/include/nodes/execnodes.h | 26 +
4 files changed, 1419 insertions(+), 13 deletions(-)
diff --git a/src/backend/executor/nodeWindowAgg.c b/src/backend/executor/nodeWindowAgg.c
index 77724a6daa..2e1baef7ea 100644
--- a/src/backend/executor/nodeWindowAgg.c
+++ b/src/backend/executor/nodeWindowAgg.c
@@ -36,6 +36,7 @@
#include "access/htup_details.h"
#include "catalog/objectaccess.h"
#include "catalog/pg_aggregate.h"
+#include "catalog/pg_collation_d.h"
#include "catalog/pg_proc.h"
#include "executor/executor.h"
#include "executor/nodeWindowAgg.h"
@@ -48,6 +49,7 @@
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/datum.h"
+#include "utils/fmgroids.h"
#include "utils/expandeddatum.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
@@ -159,6 +161,40 @@ typedef struct WindowStatePerAggData
bool restart; /* need to restart this agg in this cycle? */
} WindowStatePerAggData;
+/*
+ * Set of StringInfo. Used in RPR.
+ */
+typedef struct StringSet {
+ StringInfo *str_set;
+ Size set_size; /* current array allocation size in number of items */
+ int set_index; /* current used size */
+} StringSet;
+
+/*
+ * Allowed subsequent PATTERN variables positions.
+ * Used in RPR.
+ *
+ * pos represents the pattern variable defined order in DEFINE caluase. For
+ * example. "DEFINE START..., UP..., DOWN ..." and "PATTERN START UP DOWN UP"
+ * will create:
+ * VariablePos[0].pos[0] = 0; START
+ * VariablePos[1].pos[0] = 1; UP
+ * VariablePos[1].pos[1] = 3; UP
+ * VariablePos[2].pos[0] = 2; DOWN
+ *
+ * Note that UP has two pos because UP appears in PATTERN twice.
+ *
+ * By using this strucrture, we can know which pattern variable can be followed
+ * by which pattern variable(s). For example, START can be followed by UP and
+ * DOWN since START's pos is 0, and UP's pos is 1 or 3, DOWN's pos is 2.
+ * DOWN can be followed by UP since UP's pos is either 1 or 3.
+ *
+ */
+#define NUM_ALPHABETS 26 /* we allow [a-z] variable initials */
+typedef struct VariablePos {
+ int pos[NUM_ALPHABETS]; /* postion(s) in PATTERN */
+} VariablePos;
+
static void initialize_windowaggregate(WindowAggState *winstate,
WindowStatePerFunc perfuncstate,
WindowStatePerAgg peraggstate);
@@ -182,8 +218,9 @@ static void begin_partition(WindowAggState *winstate);
static void spool_tuples(WindowAggState *winstate, int64 pos);
static void release_partition(WindowAggState *winstate);
-static int row_is_in_frame(WindowAggState *winstate, int64 pos,
+static int row_is_in_frame(WindowAggState *winstate, int64 pos,
TupleTableSlot *slot);
+
static void update_frameheadpos(WindowAggState *winstate);
static void update_frametailpos(WindowAggState *winstate);
static void update_grouptailpos(WindowAggState *winstate);
@@ -195,9 +232,43 @@ static Datum GetAggInitVal(Datum textInitVal, Oid transtype);
static bool are_peers(WindowAggState *winstate, TupleTableSlot *slot1,
TupleTableSlot *slot2);
-static bool window_gettupleslot(WindowObject winobj, int64 pos,
- TupleTableSlot *slot);
+static int WinGetSlotInFrame(WindowObject winobj, TupleTableSlot *slot,
+ int relpos, int seektype, bool set_mark,
+ bool *isnull, bool *isout);
+static bool window_gettupleslot(WindowObject winobj, int64 pos, TupleTableSlot *slot);
+
+static void attno_map(Node *node);
+static bool attno_map_walker(Node *node, void *context);
+static int row_is_in_reduced_frame(WindowObject winobj, int64 pos);
+static bool rpr_is_defined(WindowAggState *winstate);
+
+static void create_reduced_frame_map(WindowAggState *winstate);
+static int get_reduced_frame_map(WindowAggState *winstate, int64 pos);
+static void register_reduced_frame_map(WindowAggState *winstate, int64 pos, int val);
+static void clear_reduced_frame_map(WindowAggState *winstate);
+static void update_reduced_frame(WindowObject winobj, int64 pos);
+
+static int64 evaluate_pattern(WindowObject winobj, int64 current_pos,
+ char *vname, StringInfo encoded_str, bool *result);
+
+static bool get_slots(WindowObject winobj, int64 current_pos);
+
+//static int search_str_set(char *pattern, StringSet *str_set, int *initial_orders);
+static int search_str_set(char *pattern, StringSet *str_set, VariablePos *variable_pos);
+static char pattern_initial(WindowAggState *winstate, char *vname);
+static int do_pattern_match(char *pattern, char *encoded_str);
+
+static StringSet *string_set_init(void);
+static void string_set_add(StringSet *string_set, StringInfo str);
+static StringInfo string_set_get(StringSet *string_set, int index);
+static int string_set_get_size(StringSet *string_set);
+static void string_set_discard(StringSet *string_set);
+static VariablePos *variable_pos_init(void);
+static void variable_pos_register(VariablePos *variable_pos, char initial, int pos);
+static bool variable_pos_compare(VariablePos *variable_pos, char initial1, char initial2);
+static int variable_pos_fetch(VariablePos *variable_pos, char initial, int index);
+static void variable_pos_discard(VariablePos *variable_pos);
/*
* initialize_windowaggregate
@@ -673,6 +744,7 @@ eval_windowaggregates(WindowAggState *winstate)
WindowObject agg_winobj;
TupleTableSlot *agg_row_slot;
TupleTableSlot *temp_slot;
+ bool agg_result_isnull;
numaggs = winstate->numaggs;
if (numaggs == 0)
@@ -778,6 +850,9 @@ eval_windowaggregates(WindowAggState *winstate)
* Note that we don't strictly need to restart in the last case, but if
* we're going to remove all rows from the aggregation anyway, a restart
* surely is faster.
+ *
+ * - if RPR is enabled and skip mode is SKIP TO NEXT ROW,
+ * we restart aggregation too.
*----------
*/
numaggs_restart = 0;
@@ -788,8 +863,11 @@ eval_windowaggregates(WindowAggState *winstate)
(winstate->aggregatedbase != winstate->frameheadpos &&
!OidIsValid(peraggstate->invtransfn_oid)) ||
(winstate->frameOptions & FRAMEOPTION_EXCLUSION) ||
- winstate->aggregatedupto <= winstate->frameheadpos)
+ winstate->aggregatedupto <= winstate->frameheadpos ||
+ (rpr_is_defined(winstate) &&
+ winstate->rpSkipTo == ST_NEXT_ROW))
{
+ elog(DEBUG1, "peraggstate->restart is set");
peraggstate->restart = true;
numaggs_restart++;
}
@@ -861,8 +939,10 @@ eval_windowaggregates(WindowAggState *winstate)
* If we created a mark pointer for aggregates, keep it pushed up to frame
* head, so that tuplestore can discard unnecessary rows.
*/
+#ifdef NOT_USED
if (agg_winobj->markptr >= 0)
WinSetMarkPosition(agg_winobj, winstate->frameheadpos);
+#endif
/*
* Now restart the aggregates that require it.
@@ -917,6 +997,29 @@ eval_windowaggregates(WindowAggState *winstate)
{
winstate->aggregatedupto = winstate->frameheadpos;
ExecClearTuple(agg_row_slot);
+
+ /*
+ * If RPR is defined, we do not use aggregatedupto_nonrestarted. To
+ * avoid assertion failure below, we reset aggregatedupto_nonrestarted
+ * to frameheadpos.
+ */
+ if (rpr_is_defined(winstate))
+ aggregatedupto_nonrestarted = winstate->frameheadpos;
+ }
+
+ agg_result_isnull = false;
+ /* RPR is defined? */
+ if (rpr_is_defined(winstate))
+ {
+ /*
+ * If the skip mode is SKIP TO PAST LAST ROW and we already know that
+ * current row is a skipped row, we don't need to accumulate rows,
+ * just return NULL. Note that for unamtched row, we need to do
+ * aggregation so that count(*) shows 0, rather than NULL.
+ */
+ if (winstate->rpSkipTo == ST_PAST_LAST_ROW &&
+ get_reduced_frame_map(winstate, winstate->currentpos) == RF_SKIPPED)
+ agg_result_isnull = true;
}
/*
@@ -930,6 +1033,11 @@ eval_windowaggregates(WindowAggState *winstate)
{
int ret;
+ elog(DEBUG1, "===== loop in frame starts: " INT64_FORMAT, winstate->aggregatedupto);
+
+ if (agg_result_isnull)
+ break;
+
/* Fetch next row if we didn't already */
if (TupIsNull(agg_row_slot))
{
@@ -945,9 +1053,28 @@ eval_windowaggregates(WindowAggState *winstate)
ret = row_is_in_frame(winstate, winstate->aggregatedupto, agg_row_slot);
if (ret < 0)
break;
+
if (ret == 0)
goto next_tuple;
+ if (rpr_is_defined(winstate))
+ {
+ /*
+ * If the row status at currentpos is already decided and current
+ * row status is not decided yet, it means we passed the last
+ * reduced frame. Time to break the loop.
+ */
+ if (get_reduced_frame_map(winstate, winstate->currentpos) != RF_NOT_DETERMINED &&
+ get_reduced_frame_map(winstate, winstate->aggregatedupto) == RF_NOT_DETERMINED)
+ break;
+ /*
+ * Otherwise we need to calculate the reduced frame.
+ */
+ ret = row_is_in_reduced_frame(winstate->agg_winobj, winstate->aggregatedupto);
+ if (ret == -1) /* unmatched row */
+ break;
+ }
+
/* Set tuple context for evaluation of aggregate arguments */
winstate->tmpcontext->ecxt_outertuple = agg_row_slot;
@@ -976,6 +1103,7 @@ next_tuple:
ExecClearTuple(agg_row_slot);
}
+
/* The frame's end is not supposed to move backwards, ever */
Assert(aggregatedupto_nonrestarted <= winstate->aggregatedupto);
@@ -996,6 +1124,16 @@ next_tuple:
peraggstate,
result, isnull);
+ /*
+ * RPR is defined and we just return NULL because skip mode is SKIP
+ * TO PAST LAST ROW and current row is skipped row.
+ */
+ if (agg_result_isnull)
+ {
+ *isnull = true;
+ *result = (Datum) 0;
+ }
+
/*
* save the result in case next row shares the same frame.
*
@@ -1090,6 +1228,7 @@ begin_partition(WindowAggState *winstate)
winstate->framehead_valid = false;
winstate->frametail_valid = false;
winstate->grouptail_valid = false;
+ create_reduced_frame_map(winstate);
winstate->spooled_rows = 0;
winstate->currentpos = 0;
winstate->frameheadpos = 0;
@@ -2053,6 +2192,8 @@ ExecWindowAgg(PlanState *pstate)
CHECK_FOR_INTERRUPTS();
+ elog(DEBUG1, "ExecWindowAgg called. pos: " INT64_FORMAT , winstate->currentpos);
+
if (winstate->status == WINDOWAGG_DONE)
return NULL;
@@ -2221,6 +2362,17 @@ ExecWindowAgg(PlanState *pstate)
/* don't evaluate the window functions when we're in pass-through mode */
if (winstate->status == WINDOWAGG_RUN)
{
+ /*
+ * If RPR is defined and skip mode is next row, we need to clear existing
+ * reduced frame info so that we newly calculate the info starting from
+ * current row.
+ */
+ if (rpr_is_defined(winstate))
+ {
+ if (winstate->rpSkipTo == ST_NEXT_ROW)
+ clear_reduced_frame_map(winstate);
+ }
+
/*
* Evaluate true window functions
*/
@@ -2388,6 +2540,9 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
TupleDesc scanDesc;
ListCell *l;
+ TargetEntry *te;
+ Expr *expr;
+
/* check for unsupported flags */
Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
@@ -2483,6 +2638,16 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
winstate->temp_slot_2 = ExecInitExtraTupleSlot(estate, scanDesc,
&TTSOpsMinimalTuple);
+ winstate->prev_slot = ExecInitExtraTupleSlot(estate, scanDesc,
+ &TTSOpsMinimalTuple);
+
+ winstate->next_slot = ExecInitExtraTupleSlot(estate, scanDesc,
+ &TTSOpsMinimalTuple);
+
+ winstate->null_slot = ExecInitExtraTupleSlot(estate, scanDesc,
+ &TTSOpsMinimalTuple);
+ winstate->null_slot = ExecStoreAllNullTuple(winstate->null_slot);
+
/*
* create frame head and tail slots only if needed (must create slots in
* exactly the same cases that update_frameheadpos and update_frametailpos
@@ -2667,6 +2832,39 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
winstate->inRangeAsc = node->inRangeAsc;
winstate->inRangeNullsFirst = node->inRangeNullsFirst;
+ /* Set up SKIP TO type */
+ winstate->rpSkipTo = node->rpSkipTo;
+ /* Set up row pattern recognition PATTERN clause */
+ winstate->patternVariableList = node->patternVariable;
+ winstate->patternRegexpList = node->patternRegexp;
+
+ /* Set up row pattern recognition DEFINE clause */
+ winstate->defineInitial = node->defineInitial;
+ winstate->defineVariableList = NIL;
+ winstate->defineClauseList = NIL;
+ if (node->defineClause != NIL)
+ {
+ /*
+ * Tweak arg var of PREV/NEXT so that it refers to scan/inner slot.
+ */
+ foreach(l, node->defineClause)
+ {
+ char *name;
+ ExprState *exps;
+
+ te = lfirst(l);
+ name = te->resname;
+ expr = te->expr;
+
+ elog(DEBUG1, "defineVariable name: %s", name);
+ winstate->defineVariableList = lappend(winstate->defineVariableList,
+ makeString(pstrdup(name)));
+ attno_map((Node *)expr);
+ exps = ExecInitExpr(expr, (PlanState *) winstate);
+ winstate->defineClauseList = lappend(winstate->defineClauseList, exps);
+ }
+ }
+
winstate->all_first = true;
winstate->partition_spooled = false;
winstate->more_partitions = false;
@@ -2674,6 +2872,57 @@ ExecInitWindowAgg(WindowAgg *node, EState *estate, int eflags)
return winstate;
}
+/*
+ * Rewrite varno of Var node that is the argument of PREV/NET so that it sees
+ * scan tuple (PREV) or inner tuple (NEXT).
+ */
+static void
+attno_map(Node *node)
+{
+ (void) expression_tree_walker(node, attno_map_walker, NULL);
+}
+
+static bool
+attno_map_walker(Node *node, void *context)
+{
+ FuncExpr *func;
+ int nargs;
+ Expr *expr;
+ Var *var;
+
+ if (node == NULL)
+ return false;
+
+ if (IsA(node, FuncExpr))
+ {
+ func = (FuncExpr *)node;
+
+ if (func->funcid == F_PREV || func->funcid == F_NEXT)
+ {
+ /* sanity check */
+ nargs = list_length(func->args);
+ if (list_length(func->args) != 1)
+ elog(ERROR, "PREV/NEXT must have 1 argument but function %d has %d args", func->funcid, nargs);
+
+ expr = (Expr *) lfirst(list_head(func->args));
+ if (!IsA(expr, Var))
+ elog(ERROR, "PREV/NEXT's arg is not Var"); /* XXX: is it possible that arg type is Const? */
+ var = (Var *)expr;
+
+ if (func->funcid == F_PREV)
+ /*
+ * Rewrite varno from OUTER_VAR to regular var no so that the
+ * var references scan tuple.
+ */
+ var->varno = var->varnosyn;
+ else
+ var->varno = INNER_VAR;
+ elog(DEBUG1, "PREV/NEXT's varno is rewritten to: %d", var->varno);
+ }
+ }
+ return expression_tree_walker(node, attno_map_walker, NULL);
+}
+
/* -----------------
* ExecEndWindowAgg
* -----------------
@@ -2723,6 +2972,8 @@ ExecReScanWindowAgg(WindowAggState *node)
ExecClearTuple(node->agg_row_slot);
ExecClearTuple(node->temp_slot_1);
ExecClearTuple(node->temp_slot_2);
+ ExecClearTuple(node->prev_slot);
+ ExecClearTuple(node->next_slot);
if (node->framehead_slot)
ExecClearTuple(node->framehead_slot);
if (node->frametail_slot)
@@ -3083,7 +3334,7 @@ window_gettupleslot(WindowObject winobj, int64 pos, TupleTableSlot *slot)
return false;
if (pos < winobj->markpos)
- elog(ERROR, "cannot fetch row before WindowObject's mark position");
+ elog(ERROR, "cannot fetch row: " INT64_FORMAT " before WindowObject's mark position: " INT64_FORMAT, pos, winobj->markpos );
oldcontext = MemoryContextSwitchTo(winstate->ss.ps.ps_ExprContext->ecxt_per_query_memory);
@@ -3403,14 +3654,54 @@ WinGetFuncArgInFrame(WindowObject winobj, int argno,
WindowAggState *winstate;
ExprContext *econtext;
TupleTableSlot *slot;
- int64 abs_pos;
- int64 mark_pos;
Assert(WindowObjectIsValid(winobj));
winstate = winobj->winstate;
econtext = winstate->ss.ps.ps_ExprContext;
slot = winstate->temp_slot_1;
+ if (WinGetSlotInFrame(winobj, slot,
+ relpos, seektype, set_mark,
+ isnull, isout) == 0)
+ {
+ econtext->ecxt_outertuple = slot;
+ return ExecEvalExpr((ExprState *) list_nth(winobj->argstates, argno),
+ econtext, isnull);
+ }
+
+ if (isout)
+ *isout = true;
+ *isnull = true;
+ return (Datum) 0;
+}
+
+/*
+ * WinGetSlotInFrame
+ * slot: TupleTableSlot to store the result
+ * relpos: signed rowcount offset from the seek position
+ * seektype: WINDOW_SEEK_HEAD or WINDOW_SEEK_TAIL
+ * set_mark: If the row is found/in frame and set_mark is true, the mark is
+ * moved to the row as a side-effect.
+ * isnull: output argument, receives isnull status of result
+ * isout: output argument, set to indicate whether target row position
+ * is out of frame (can pass NULL if caller doesn't care about this)
+ *
+ * Returns 0 if we successfullt got the slot. false if out of frame.
+ * (also isout is set)
+ */
+static int
+WinGetSlotInFrame(WindowObject winobj, TupleTableSlot *slot,
+ int relpos, int seektype, bool set_mark,
+ bool *isnull, bool *isout)
+{
+ WindowAggState *winstate;
+ int64 abs_pos;
+ int64 mark_pos;
+ int num_reduced_frame;
+
+ Assert(WindowObjectIsValid(winobj));
+ winstate = winobj->winstate;
+
switch (seektype)
{
case WINDOW_SEEK_CURRENT:
@@ -3477,11 +3768,21 @@ WinGetFuncArgInFrame(WindowObject winobj, int argno,
winstate->frameOptions);
break;
}
+ num_reduced_frame = row_is_in_reduced_frame(winobj, winstate->frameheadpos);
+ if (num_reduced_frame < 0)
+ goto out_of_frame;
+ else if (num_reduced_frame > 0)
+ if (relpos >= num_reduced_frame)
+ goto out_of_frame;
break;
case WINDOW_SEEK_TAIL:
/* rejecting relpos > 0 is easy and simplifies code below */
if (relpos > 0)
goto out_of_frame;
+
+ /* RPR cares about frame head pos. Need to call update_frameheadpos */
+ update_frameheadpos(winstate);
+
update_frametailpos(winstate);
abs_pos = winstate->frametailpos - 1 + relpos;
@@ -3548,6 +3849,12 @@ WinGetFuncArgInFrame(WindowObject winobj, int argno,
mark_pos = 0; /* keep compiler quiet */
break;
}
+
+ num_reduced_frame = row_is_in_reduced_frame(winobj, winstate->frameheadpos + relpos);
+ if (num_reduced_frame < 0)
+ goto out_of_frame;
+ else if (num_reduced_frame > 0)
+ abs_pos = winstate->frameheadpos + relpos + num_reduced_frame - 1;
break;
default:
elog(ERROR, "unrecognized window seek type: %d", seektype);
@@ -3566,15 +3873,13 @@ WinGetFuncArgInFrame(WindowObject winobj, int argno,
*isout = false;
if (set_mark)
WinSetMarkPosition(winobj, mark_pos);
- econtext->ecxt_outertuple = slot;
- return ExecEvalExpr((ExprState *) list_nth(winobj->argstates, argno),
- econtext, isnull);
+ return 0;
out_of_frame:
if (isout)
*isout = true;
*isnull = true;
- return (Datum) 0;
+ return -1;
}
/*
@@ -3605,3 +3910,1039 @@ WinGetFuncArgCurrent(WindowObject winobj, int argno, bool *isnull)
return ExecEvalExpr((ExprState *) list_nth(winobj->argstates, argno),
econtext, isnull);
}
+
+/*
+ * rpr_is_defined
+ * return true if Row pattern recognition is defined.
+ */
+static
+bool rpr_is_defined(WindowAggState *winstate)
+{
+ return winstate->patternVariableList != NIL;
+}
+
+/*
+ * row_is_in_reduced_frame
+ * Determine whether a row is in the current row's reduced window frame according
+ * to row pattern matching
+ *
+ * The row must has been already determined that it is in a full window frame
+ * and fetched it into slot.
+ *
+ * Returns:
+ * = 0, RPR is not defined.
+ * >0, if the row is the first in the reduced frame. Return the number of rows in the reduced frame.
+ * -1, if the row is unmatched row
+ * -2, if the row is in the reduced frame but needed to be skipped because of
+ * AFTER MATCH SKIP PAST LAST ROW
+ */
+static
+int row_is_in_reduced_frame(WindowObject winobj, int64 pos)
+{
+ WindowAggState *winstate = winobj->winstate;
+ int state;
+ int rtn;
+
+ if (!rpr_is_defined(winstate))
+ {
+ /*
+ * RPR is not defined. Assume that we are always in the the reduced
+ * window frame.
+ */
+ rtn = 0;
+ elog(DEBUG1, "row_is_in_reduced_frame returns %d: pos: " INT64_FORMAT, rtn, pos);
+ return rtn;
+ }
+
+ state = get_reduced_frame_map(winstate, pos);
+
+ if (state == RF_NOT_DETERMINED)
+ {
+ update_frameheadpos(winstate);
+ update_reduced_frame(winobj, pos);
+ }
+
+ state = get_reduced_frame_map(winstate, pos);
+
+ switch (state)
+ {
+ int64 i;
+ int num_reduced_rows;
+
+ case RF_FRAME_HEAD:
+ num_reduced_rows = 1;
+ for (i = pos + 1; get_reduced_frame_map(winstate,i) == RF_SKIPPED; i++)
+ num_reduced_rows++;
+ rtn = num_reduced_rows;
+ break;
+
+ case RF_SKIPPED:
+ rtn = -2;
+ break;
+
+ case RF_UNMATCHED:
+ rtn = -1;
+ break;
+
+ default:
+ elog(ERROR, "Unrecognized state: %d at: " INT64_FORMAT, state, pos);
+ break;
+ }
+
+ elog(DEBUG1, "row_is_in_reduced_frame returns %d: pos: " INT64_FORMAT, rtn, pos);
+ return rtn;
+}
+
+#define REDUCED_FRAME_MAP_INIT_SIZE 1024L
+
+/*
+ * Create reduced frame map
+ */
+static
+void create_reduced_frame_map(WindowAggState *winstate)
+{
+ winstate->reduced_frame_map =
+ MemoryContextAlloc(winstate->partcontext, REDUCED_FRAME_MAP_INIT_SIZE);
+ winstate->alloc_sz = REDUCED_FRAME_MAP_INIT_SIZE;
+ clear_reduced_frame_map(winstate);
+}
+
+/*
+ * Clear reduced frame map
+ */
+static
+void clear_reduced_frame_map(WindowAggState *winstate)
+{
+ Assert(winstate->reduced_frame_map != NULL);
+ MemSet(winstate->reduced_frame_map, RF_NOT_DETERMINED,
+ winstate->alloc_sz);
+}
+
+/*
+ * Get reduced frame map specified by pos
+ */
+static
+int get_reduced_frame_map(WindowAggState *winstate, int64 pos)
+{
+ Assert(winstate->reduced_frame_map != NULL);
+
+ if (pos < 0 || pos >= winstate->alloc_sz)
+ elog(ERROR, "wrong pos: " INT64_FORMAT, pos);
+
+ return winstate->reduced_frame_map[pos];
+}
+
+/*
+ * Add/replace reduced frame map member at pos.
+ * If there's no enough space, expand the map.
+ */
+static
+void register_reduced_frame_map(WindowAggState *winstate, int64 pos, int val)
+{
+ int64 realloc_sz;
+
+ Assert(winstate->reduced_frame_map != NULL);
+
+ if (pos < 0)
+ elog(ERROR, "wrong pos: " INT64_FORMAT, pos);
+
+ if (pos > winstate->alloc_sz - 1)
+ {
+ realloc_sz = winstate->alloc_sz * 2;
+
+ winstate->reduced_frame_map =
+ repalloc(winstate->reduced_frame_map, realloc_sz);
+
+ MemSet(winstate->reduced_frame_map + winstate->alloc_sz,
+ RF_NOT_DETERMINED, realloc_sz - winstate->alloc_sz);
+
+ winstate->alloc_sz = realloc_sz;
+ }
+
+ winstate->reduced_frame_map[pos] = val;
+}
+
+/*
+ * update_reduced_frame
+ * Update reduced frame info.
+ */
+static
+void update_reduced_frame(WindowObject winobj, int64 pos)
+{
+ WindowAggState *winstate = winobj->winstate;
+ ListCell *lc1, *lc2;
+ bool expression_result;
+ int num_matched_rows;
+ int64 original_pos;
+ bool anymatch;
+ StringInfo encoded_str;
+ StringInfo pattern_str = makeStringInfo();
+ StringSet *str_set;
+ int str_set_index = 0;
+ int initial_index;
+ VariablePos *variable_pos;
+
+ /*
+ * Set of pattern variables evaluated to true.
+ * Each character corresponds to pattern variable.
+ * Example:
+ * str_set[0] = "AB";
+ * str_set[1] = "AC";
+ * In this case at row 0 A and B are true, and A and C are true in row 1.
+ */
+
+ /* initialize pattern variables set */
+ str_set = string_set_init();
+
+ /* save original pos */
+ original_pos = pos;
+
+ /*
+ * Loop over until none of pattern matches or encounters end of frame.
+ */
+ for (;;)
+ {
+ int64 result_pos = -1;
+
+ /*
+ * Loop over each PATTERN variable.
+ */
+ anymatch = false;
+ encoded_str = makeStringInfo();
+
+ forboth(lc1, winstate->patternVariableList, lc2, winstate->patternRegexpList)
+ {
+ char *vname = strVal(lfirst(lc1));
+ char *quantifier = strVal(lfirst(lc2));
+
+ elog(DEBUG1, "pos: " INT64_FORMAT " pattern vname: %s quantifier: %s", pos, vname, quantifier);
+
+ expression_result = false;
+
+ /* evaluate row pattern against current row */
+ result_pos = evaluate_pattern(winobj, pos, vname, encoded_str, &expression_result);
+ if (expression_result)
+ {
+ elog(DEBUG1, "expression result is true");
+ anymatch = true;
+ }
+
+ /*
+ * If out of frame, we are done.
+ */
+ if (result_pos < 0)
+ break;
+ }
+
+ if (!anymatch)
+ {
+ /* none of patterns matched. */
+ break;
+ }
+
+ string_set_add(str_set, encoded_str);
+
+ elog(DEBUG1, "pos: " INT64_FORMAT " str_set_index: %d encoded_str: %s", pos, str_set_index, encoded_str->data);
+
+ /* move to next row */
+ pos++;
+
+ if (result_pos < 0)
+ {
+ /* out of frame */
+ break;
+ }
+ }
+
+ if (string_set_get_size(str_set) == 0)
+ {
+ /* no match found in the first row */
+ register_reduced_frame_map(winstate, original_pos, RF_UNMATCHED);
+ return;
+ }
+
+ elog(DEBUG2, "pos: " INT64_FORMAT " encoded_str: %s", pos, encoded_str->data);
+
+ /* build regular expression */
+ pattern_str = makeStringInfo();
+ appendStringInfoChar(pattern_str, '^');
+ initial_index = 0;
+
+ variable_pos = variable_pos_init();
+
+ forboth (lc1, winstate->patternVariableList, lc2, winstate->patternRegexpList)
+ {
+ char *vname = strVal(lfirst(lc1));
+ char *quantifier = strVal(lfirst(lc2));
+ char initial;
+
+ initial = pattern_initial(winstate, vname);
+ Assert(initial != 0);
+ appendStringInfoChar(pattern_str, initial);
+ if (quantifier[0])
+ appendStringInfoChar(pattern_str, quantifier[0]);
+
+ /*
+ * Register the initial at initial_index. If the initial appears more
+ * than once, all of it's initial_index will be recorded. This could
+ * happen if a pattern variable appears in the PATTERN clause more
+ * than once like "UP DOWN UP" "UP UP UP".
+ */
+ variable_pos_register(variable_pos, initial, initial_index);
+
+ initial_index++;
+ }
+
+ elog(DEBUG2, "pos: " INT64_FORMAT " pattern: %s", pos, pattern_str->data);
+
+ /* look for matching pattern variable sequence */
+ elog(DEBUG1, "search_str_set started");
+ num_matched_rows = search_str_set(pattern_str->data, str_set, variable_pos);
+ elog(DEBUG1, "search_str_set returns: %d", num_matched_rows);
+
+ variable_pos_discard(variable_pos);
+ string_set_discard(str_set);
+
+ /*
+ * We are at the first row in the reduced frame. Save the number of
+ * matched rows as the number of rows in the reduced frame.
+ */
+ if (num_matched_rows <= 0)
+ {
+ /* no match */
+ register_reduced_frame_map(winstate, original_pos, RF_UNMATCHED);
+ }
+ else
+ {
+ int64 i;
+
+ register_reduced_frame_map(winstate, original_pos, RF_FRAME_HEAD);
+
+ for (i = original_pos + 1; i < original_pos + num_matched_rows; i++)
+ {
+ register_reduced_frame_map(winstate, i, RF_SKIPPED);
+ }
+ }
+
+ return;
+}
+
+/*
+ * Perform pattern matching using pattern against str_set. pattern is a
+ * regular expression derived from PATTERN clause. Note that the regular
+ * expression string is prefixed by '^' and followed by initials represented
+ * in a same way as str_set. str_set is a set of StringInfo. Each StringInfo
+ * has a string comprising initials of pattern variable strings being true in
+ * a row. The initials are one of [a-y], parallel to the order of variable
+ * names in DEFINE clause. For example, if DEFINE has variables START, UP and
+ * DOWN, PATTERN HAS START, UP and DOWN, then the initials in PATTERN will be
+ * 'a', 'b' and 'c'.
+ *
+ * variable_pos is an array representing the order of pattern variable string
+ * initials in PATTERN clause. For example initial 'a' potion is in
+ * variable_pos[0].pos[0] = 0. Note that if the pattern is "START UP DOWN UP"
+ * (UP appears twice), then "UP" (initial is 'b') has two position 1 and
+ * 3. Thus variable_pos for b is variable_pos[1].pos[0] = 1 and
+ * variable_pos[1].pos[1] = 3.
+ *
+ * Returns the longest number of the matching rows.
+ */
+static
+int search_str_set(char *pattern, StringSet *str_set, VariablePos *variable_pos)
+{
+#define MAX_CANDIDATE_NUM 10000 /* max pattern match candidate size */
+#define FREEZED_CHAR 'Z' /* a pattern is freezed if it ends with the char */
+#define DISCARD_CHAR 'z' /* a pattern is not need to keep */
+
+ int set_size; /* number of rows in the set */
+ int resultlen;
+ int index;
+ StringSet *old_str_set, *new_str_set;
+ int new_str_size;
+ int len;
+
+ set_size = string_set_get_size(str_set);
+ new_str_set = string_set_init();
+ len = 0;
+ resultlen = 0;
+
+ /*
+ * Generate all possible pattern variable name initials as a set of
+ * StringInfo named "new_str_set". For example, if we have two rows
+ * having "ab" (row 0) and "ac" (row 1) in the input str_set, new_str_set
+ * will have set of StringInfo "aa", "ac", "ba" and "bc" in the end.
+ */
+ elog(DEBUG1, "pattern: %s set_size: %d", pattern, set_size);
+ for (index = 0; index < set_size; index++)
+ {
+ StringInfo str; /* search target row */
+ char *p;
+ int old_set_size;
+ int i;
+
+ elog(DEBUG1, "index: %d", index);
+
+ if (index == 0)
+ {
+ /* copy variables in row 0 */
+ str = string_set_get(str_set, index);
+ p = str->data;
+
+ /*
+ * Loop over each new pattern variable char.
+ */
+ while (*p)
+ {
+ StringInfo new = makeStringInfo();
+
+ /* add pattern variable char */
+ appendStringInfoChar(new, *p);
+ /* add new one to string set */
+ string_set_add(new_str_set, new);
+ elog(DEBUG1, "old_str: NULL new_str: %s", new->data);
+ p++; /* next pattern variable */
+ }
+ }
+ else /* index != 0 */
+ {
+ old_str_set = new_str_set;
+ new_str_set = string_set_init();
+ str = string_set_get(str_set, index);
+ old_set_size = string_set_get_size(old_str_set);
+
+ /*
+ * Loop over each rows in the previous result set.
+ */
+ for (i = 0; i < old_set_size ; i++)
+ {
+ StringInfo new;
+ char last_old_char;
+ int old_str_len;
+ StringInfo old = string_set_get(old_str_set, i);
+
+ p = old->data;
+ old_str_len = strlen(p);
+ if (old_str_len > 0)
+ last_old_char = p[old_str_len - 1];
+ else
+ last_old_char = '\0';
+
+ /* Is this old set freezed? */
+ if (last_old_char == FREEZED_CHAR)
+ {
+ /* if shorter match. we can discard it */
+ if ((old_str_len - 1) < resultlen)
+ {
+ elog(DEBUG1, "discard this old set because shorter match: %s", old->data);
+ continue;
+ }
+
+ elog(DEBUG1, "keep this old set: %s", old->data);
+ new = makeStringInfo();
+ appendStringInfoString(new, old->data);
+ string_set_add(new_str_set, new);
+ continue;
+ }
+ /* Can this old set be discarded? */
+ else if (last_old_char == DISCARD_CHAR)
+ {
+ elog(DEBUG1, "discard this old set: %s", old->data);
+ continue;
+ }
+
+ elog(DEBUG1, "str->data: %s", str->data);
+
+ /*
+ * loop over each pattern variable initial char in the input
+ * set.
+ */
+ for (p = str->data; *p; p++)
+ {
+ /*
+ * Optimization. Check if the row's pattern variable
+ * initial character position is greater than or equal to
+ * the old set's last pattern variable initial character
+ * position. For example, if the old set's last pattern
+ * variable initials are "ab", then the new pattern
+ * variable initial can be "b" or "c" but can not be "a",
+ * if the initials in PATTERN is something like "a b c" or
+ * "a b+ c+" etc. This optimization is possible when we
+ * only allow "+" quantifier.
+ */
+ if (variable_pos_compare(variable_pos, last_old_char, *p))
+ {
+ /* copy source string */
+ new = makeStringInfo();
+ appendStringInfoString(new, old->data);
+ /* add pattern variable char */
+ appendStringInfoChar(new, *p);
+ elog(DEBUG1, "old_str: %s new_str: %s", old->data, new->data);
+
+ /*
+ * Adhoc optimization. If the first letter in the
+ * input string is the first and second position one
+ * and there's no associated quatifier '+', then we
+ * can dicard the input because there's no chace to
+ * expand the string further.
+ *
+ * For example, pattern "abc" cannot match "aa".
+ */
+ elog(DEBUG1, "pattern[1]:%c pattern[2]:%c new[0]:%c new[1]:%c",
+ pattern[1], pattern[2], new->data[0], new->data[1]);
+ if (pattern[1] == new->data[0] &&
+ pattern[1] == new->data[1] &&
+ pattern[2] != '+' &&
+ pattern[1] != pattern[2])
+ {
+ elog(DEBUG1, "discard this new data: %s",
+ new->data);
+ pfree(new->data);
+ pfree(new);
+ continue;
+ }
+
+ /* add new one to string set */
+ string_set_add(new_str_set, new);
+ }
+ else
+ {
+ /*
+ * We are freezing this pattern string. Since there's
+ * no chance to expand the string further, we perform
+ * pattern matching against the string. If it does not
+ * match, we can discard it.
+ */
+ len = do_pattern_match(pattern, old->data);
+
+ if (len <= 0)
+ {
+ /* no match. we can discard it */
+ continue;
+ }
+
+ else if (len <= resultlen)
+ {
+ /* shorter match. we can discard it */
+ continue;
+ }
+ else
+ {
+ /* match length is the longest so far */
+
+ int new_index;
+
+ /* remember the longest match */
+ resultlen = len;
+
+ /* freeze the pattern string */
+ new = makeStringInfo();
+ appendStringInfoString(new, old->data);
+ /* add freezed mark */
+ appendStringInfoChar(new, FREEZED_CHAR);
+ elog(DEBUG1, "old_str: %s new_str: %s", old->data, new->data);
+ string_set_add(new_str_set, new);
+
+ /*
+ * Search new_str_set to find out freezed
+ * entries that have shorter match length.
+ * Mark them as "discard" so that they are
+ * discarded in the next round.
+ */
+
+ /* new_index_size should be the one before */
+ new_str_size = string_set_get_size(new_str_set) - 1;
+
+ /* loop over new_str_set */
+ for (new_index = 0; new_index < new_str_size; new_index++)
+ {
+ char new_last_char;
+ int new_str_len;
+
+ new = string_set_get(new_str_set, new_index);
+ new_str_len = strlen(new->data);
+ if (new_str_len > 0)
+ {
+ new_last_char = new->data[new_str_len - 1];
+ if (new_last_char == FREEZED_CHAR &&
+ (new_str_len - 1) <= len)
+ {
+ /* mark this set to discard in the next round */
+ appendStringInfoChar(new, DISCARD_CHAR);
+ elog(DEBUG1, "add discard char: %s", new->data);
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+ /* we no longer need old string set */
+ string_set_discard(old_str_set);
+ }
+ }
+
+ /*
+ * Perform pattern matching to find out the longest match.
+ */
+ new_str_size = string_set_get_size(new_str_set);
+ elog(DEBUG1, "new_str_size: %d", new_str_size);
+ len = 0;
+ resultlen = 0;
+
+ for (index = 0; index < new_str_size; index++)
+ {
+ StringInfo s;
+
+ s = string_set_get(new_str_set, index);
+ if (s == NULL)
+ continue; /* no data */
+
+ elog(DEBUG1, "target string: %s", s->data);
+
+ len = do_pattern_match(pattern, s->data);
+ if (len > resultlen)
+ {
+ /* remember the longest match */
+ resultlen = len;
+
+ /*
+ * If the size of result set is equal to the number of rows in the
+ * set, we are done because it's not possible that the number of
+ * matching rows exceeds the number of rows in the set.
+ */
+ if (resultlen >= set_size)
+ break;
+ }
+ }
+
+ /* we no longer need new string set */
+ string_set_discard(new_str_set);
+
+ return resultlen;
+}
+
+/*
+ * do_pattern_match
+ * perform pattern match using pattern against encoded_str.
+ * returns matching number of rows if matching is succeeded.
+ * Otherwise returns 0.
+ */
+static
+int do_pattern_match(char *pattern, char *encoded_str)
+{
+ Datum d;
+ text *res;
+ char *substr;
+ int len = 0;
+ text *pattern_text, *encoded_str_text;
+
+ pattern_text = cstring_to_text(pattern);
+ encoded_str_text = cstring_to_text(encoded_str);
+
+ /*
+ * We first perform pattern matching using regexp_instr, then call
+ * textregexsubstr to get matched substring to know how long the
+ * matched string is. That is the number of rows in the reduced window
+ * frame. The reason why we can't call textregexsubstr in the first
+ * place is, it errors out if pattern does not match.
+ */
+ if (DatumGetInt32(DirectFunctionCall2Coll(regexp_instr, DEFAULT_COLLATION_OID,
+ PointerGetDatum(encoded_str_text),
+ PointerGetDatum(pattern_text))))
+ {
+ d = DirectFunctionCall2Coll(textregexsubstr,
+ DEFAULT_COLLATION_OID,
+ PointerGetDatum(encoded_str_text),
+ PointerGetDatum(pattern_text));
+ if (d != 0)
+ {
+ res = DatumGetTextPP(d);
+ substr = text_to_cstring(res);
+ len = strlen(substr);
+ pfree(substr);
+ }
+ }
+ pfree(encoded_str_text);
+ pfree(pattern_text);
+
+ return len;
+}
+
+
+/*
+ * Evaluate expression associated with PATTERN variable vname.
+ * relpos is relative row position in a frame (starting from 0).
+ * "quantifier" is the quatifier part of the PATTERN regular expression.
+ * Currently only '+' is allowed.
+ * result is out paramater representing the expression evaluation result
+ * is true of false.
+ * Return values are:
+ * >=0: the last match absolute row position
+ * other wise out of frame.
+ */
+static
+int64 evaluate_pattern(WindowObject winobj, int64 current_pos,
+ char *vname, StringInfo encoded_str, bool *result)
+{
+ WindowAggState *winstate = winobj->winstate;
+ ExprContext *econtext = winstate->ss.ps.ps_ExprContext;
+ ListCell *lc1, *lc2, *lc3;
+ ExprState *pat;
+ Datum eval_result;
+ bool out_of_frame = false;
+ bool isnull;
+ TupleTableSlot *slot;
+
+ forthree (lc1, winstate->defineVariableList, lc2, winstate->defineClauseList, lc3, winstate->defineInitial)
+ {
+ char initial;
+ char *name = strVal(lfirst(lc1));
+
+ if (strcmp(vname, name))
+ continue;
+
+ initial = *(strVal(lfirst(lc3)));
+
+ /* set expression to evaluate */
+ pat = lfirst(lc2);
+
+ /* get current, previous and next tuples */
+ if (!get_slots(winobj, current_pos))
+ {
+ out_of_frame = true;
+ }
+ else
+ {
+ /* evaluate the expression */
+ eval_result = ExecEvalExpr(pat, econtext, &isnull);
+ if (isnull)
+ {
+ /* expression is NULL */
+ elog(DEBUG1, "expression for %s is NULL at row: " INT64_FORMAT, vname, current_pos);
+ *result = false;
+ }
+ else
+ {
+ if (!DatumGetBool(eval_result))
+ {
+ /* expression is false */
+ elog(DEBUG1, "expression for %s is false at row: " INT64_FORMAT, vname, current_pos);
+ *result = false;
+ }
+ else
+ {
+ /* expression is true */
+ elog(DEBUG1, "expression for %s is true at row: " INT64_FORMAT, vname, current_pos);
+ appendStringInfoChar(encoded_str, initial);
+ *result = true;
+ }
+ }
+
+ slot = winstate->temp_slot_1;
+ if (slot != winstate->null_slot)
+ ExecClearTuple(slot);
+ slot = winstate->prev_slot;
+ if (slot != winstate->null_slot)
+ ExecClearTuple(slot);
+ slot = winstate->next_slot;
+ if (slot != winstate->null_slot)
+ ExecClearTuple(slot);
+
+ break;
+ }
+
+ if (out_of_frame)
+ {
+ *result = false;
+ return -1;
+ }
+ }
+ return current_pos;
+}
+
+/*
+ * Get current, previous and next tuples.
+ * Returns false if current row is out of partition/full frame.
+ */
+static
+bool get_slots(WindowObject winobj, int64 current_pos)
+{
+ WindowAggState *winstate = winobj->winstate;
+ TupleTableSlot *slot;
+ int ret;
+ ExprContext *econtext;
+
+ econtext = winstate->ss.ps.ps_ExprContext;
+
+ /* set up current row tuple slot */
+ slot = winstate->temp_slot_1;
+ if (!window_gettupleslot(winobj, current_pos, slot))
+ {
+ elog(DEBUG1, "current row is out of partition at:" INT64_FORMAT, current_pos);
+ return false;
+ }
+ ret = row_is_in_frame(winstate, current_pos, slot);
+ if (ret <= 0)
+ {
+ elog(DEBUG1, "current row is out of frame at: " INT64_FORMAT, current_pos);
+ ExecClearTuple(slot);
+ return false;
+ }
+ econtext->ecxt_outertuple = slot;
+
+ /* for PREV */
+ if (current_pos > 0)
+ {
+ slot = winstate->prev_slot;
+ if (!window_gettupleslot(winobj, current_pos - 1, slot))
+ {
+ elog(DEBUG1, "previous row is out of partition at: " INT64_FORMAT, current_pos - 1);
+ econtext->ecxt_scantuple = winstate->null_slot;
+ }
+ else
+ {
+ ret = row_is_in_frame(winstate, current_pos - 1, slot);
+ if (ret <= 0)
+ {
+ elog(DEBUG1, "previous row is out of frame at: " INT64_FORMAT, current_pos - 1);
+ ExecClearTuple(slot);
+ econtext->ecxt_scantuple = winstate->null_slot;
+ }
+ else
+ {
+ econtext->ecxt_scantuple = slot;
+ }
+ }
+ }
+ else
+ econtext->ecxt_scantuple = winstate->null_slot;
+
+ /* for NEXT */
+ slot = winstate->next_slot;
+ if (!window_gettupleslot(winobj, current_pos + 1, slot))
+ {
+ elog(DEBUG1, "next row is out of partiton at: " INT64_FORMAT, current_pos + 1);
+ econtext->ecxt_innertuple = winstate->null_slot;
+ }
+ else
+ {
+ ret = row_is_in_frame(winstate, current_pos + 1, slot);
+ if (ret <= 0)
+ {
+ elog(DEBUG1, "next row is out of frame at: " INT64_FORMAT, current_pos + 1);
+ ExecClearTuple(slot);
+ econtext->ecxt_innertuple = winstate->null_slot;
+ }
+ else
+ econtext->ecxt_innertuple = slot;
+ }
+ return true;
+}
+
+/*
+ * Return pattern variable initial character
+ * matching with pattern variable name vname.
+ * If not found, return 0.
+ */
+static
+char pattern_initial(WindowAggState *winstate, char *vname)
+{
+ char initial;
+ char *name;
+ ListCell *lc1, *lc2;
+
+ forboth (lc1, winstate->defineVariableList, lc2, winstate->defineInitial)
+ {
+ name = strVal(lfirst(lc1)); /* DEFINE variable name */
+ initial = *(strVal(lfirst(lc2))); /* DEFINE variable initial */
+
+
+ if (!strcmp(name, vname))
+ return initial; /* found */
+ }
+ return 0;
+}
+
+/*
+ * string_set_init
+ * Create dynamic set of StringInfo.
+ */
+static
+StringSet *string_set_init(void)
+{
+/* Initial allocation size of str_set */
+#define STRING_SET_ALLOC_SIZE 1024
+
+ StringSet *string_set;
+ Size set_size;
+
+ string_set = palloc0(sizeof(StringSet));
+ string_set->set_index = 0;
+ set_size = STRING_SET_ALLOC_SIZE;
+ string_set->str_set = palloc(set_size * sizeof(StringInfo));
+ string_set->set_size = set_size;
+
+ return string_set;
+}
+
+/*
+ * Add StringInfo str to StringSet string_set.
+ */
+static
+void string_set_add(StringSet *string_set, StringInfo str)
+{
+ Size set_size;
+
+ set_size = string_set->set_size;
+ if (string_set->set_index >= set_size)
+ {
+ set_size *= 2;
+ string_set->str_set = repalloc(string_set->str_set,
+ set_size * sizeof(StringInfo));
+ string_set->set_size = set_size;
+ }
+
+ string_set->str_set[string_set->set_index++] = str;
+
+ return;
+}
+
+/*
+ * Returns StringInfo specified by index.
+ * If there's no data yet, returns NULL.
+ */
+static
+StringInfo string_set_get(StringSet *string_set, int index)
+{
+ /* no data? */
+ if (index == 0 && string_set->set_index == 0)
+ return NULL;
+
+ if (index < 0 ||index >= string_set->set_index)
+ elog(ERROR, "invalid index: %d", index);
+
+ return string_set->str_set[index];
+}
+
+/*
+ * Returns the size of StringSet.
+ */
+static
+int string_set_get_size(StringSet *string_set)
+{
+ return string_set->set_index;
+}
+
+/*
+ * Discard StringSet.
+ * All memory including StringSet itself is freed.
+ */
+static
+void string_set_discard(StringSet *string_set)
+{
+ int i;
+
+ for (i = 0; i < string_set->set_index; i++)
+ {
+ StringInfo str = string_set->str_set[i];
+ pfree(str->data);
+ pfree(str);
+ }
+ pfree(string_set->str_set);
+ pfree(string_set);
+}
+
+/*
+ * Create and initialize variable postion structure
+ */
+static
+VariablePos *variable_pos_init(void)
+{
+ VariablePos *variable_pos;
+
+ variable_pos = palloc(sizeof(VariablePos) * NUM_ALPHABETS);
+ MemSet(variable_pos, -1, sizeof(VariablePos) * NUM_ALPHABETS);
+ return variable_pos;
+}
+
+/*
+ * Register pattern variable whose initial is initial into postion index.
+ * pos is position of initial.
+ * If pos is already registered, register it at next empty slot.
+ */
+static
+void variable_pos_register(VariablePos *variable_pos, char initial, int pos)
+{
+ int index = initial - 'a';
+ int slot;
+ int i;
+
+ if (pos < 0 || pos > NUM_ALPHABETS)
+ elog(ERROR, "initial is not valid char: %c", initial);
+
+ for (i = 0; i < NUM_ALPHABETS; i++)
+ {
+ slot = variable_pos[index].pos[i];
+ if (slot < 0)
+ {
+ /* empty slot found */
+ variable_pos[index].pos[i] = pos;
+ return;
+ }
+ }
+ elog(ERROR, "no empty slot for initial: %c", initial);
+}
+
+/*
+ * Returns true if initial1 can be followed by initial2
+ */
+static
+bool variable_pos_compare(VariablePos *variable_pos, char initial1, char initial2)
+{
+ int index1, index2;
+ int pos1, pos2;
+
+ for (index1 = 0; ; index1++)
+ {
+ pos1 = variable_pos_fetch(variable_pos, initial1, index1);
+ if (pos1 < 0)
+ break;
+
+ for (index2 = 0; ; index2++)
+ {
+ pos2 = variable_pos_fetch(variable_pos, initial2, index2);
+ if (pos2 < 0)
+ break;
+ if (pos1 <= pos2)
+ return true;
+ }
+ }
+ return false;
+}
+
+/*
+ * Fetch position of pattern variable whose initial is initial, and whose index
+ * is index. If no postion was registered by initial, index, returns -1.
+ */
+static
+int variable_pos_fetch(VariablePos *variable_pos, char initial, int index)
+{
+ int pos = initial - 'a';
+
+ if (pos < 0 || pos > NUM_ALPHABETS)
+ elog(ERROR, "initial is not valid char: %c", initial);
+
+ if (index < 0 || index > NUM_ALPHABETS)
+ elog(ERROR, "index is not valid: %d", index);
+
+ return variable_pos[pos].pos[index];
+}
+
+/*
+ * Discard VariablePos
+ */
+static
+void variable_pos_discard(VariablePos *variable_pos)
+{
+ pfree(variable_pos);
+}
diff --git a/src/backend/utils/adt/windowfuncs.c b/src/backend/utils/adt/windowfuncs.c
index b87a624fb2..9ebcc7b5d2 100644
--- a/src/backend/utils/adt/windowfuncs.c
+++ b/src/backend/utils/adt/windowfuncs.c
@@ -13,6 +13,9 @@
*/
#include "postgres.h"
+#include "catalog/pg_collation_d.h"
+#include "executor/executor.h"
+#include "nodes/execnodes.h"
#include "nodes/supportnodes.h"
#include "utils/builtins.h"
#include "windowapi.h"
@@ -36,11 +39,19 @@ typedef struct
int64 remainder; /* (total rows) % (bucket num) */
} ntile_context;
+/*
+ * rpr process information.
+ * Used for AFTER MATCH SKIP PAST LAST ROW
+ */
+typedef struct SkipContext
+{
+ int64 pos; /* last row absolute position */
+} SkipContext;
+
static bool rank_up(WindowObject winobj);
static Datum leadlag_common(FunctionCallInfo fcinfo,
bool forward, bool withoffset, bool withdefault);
-
/*
* utility routine for *_rank functions.
*/
@@ -673,7 +684,7 @@ window_last_value(PG_FUNCTION_ARGS)
bool isnull;
result = WinGetFuncArgInFrame(winobj, 0,
- 0, WINDOW_SEEK_TAIL, true,
+ 0, WINDOW_SEEK_TAIL, false,
&isnull, NULL);
if (isnull)
PG_RETURN_NULL();
@@ -713,3 +724,25 @@ window_nth_value(PG_FUNCTION_ARGS)
PG_RETURN_DATUM(result);
}
+
+/*
+ * prev
+ * Dummy function to invoke RPR's navigation operator "PREV".
+ * This is *not* a window function.
+ */
+Datum
+window_prev(PG_FUNCTION_ARGS)
+{
+ PG_RETURN_DATUM(PG_GETARG_DATUM(0));
+}
+
+/*
+ * next
+ * Dummy function to invoke RPR's navigation operation "NEXT".
+ * This is *not* a window function.
+ */
+Datum
+window_next(PG_FUNCTION_ARGS)
+{
+ PG_RETURN_DATUM(PG_GETARG_DATUM(0));
+}
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index c92d0631a0..ebb017b015 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -10425,6 +10425,12 @@
{ oid => '3114', descr => 'fetch the Nth row value',
proname => 'nth_value', prokind => 'w', prorettype => 'anyelement',
proargtypes => 'anyelement int4', prosrc => 'window_nth_value' },
+{ oid => '6122', descr => 'previous value',
+ proname => 'prev', provolatile => 's', prorettype => 'anyelement',
+ proargtypes => 'anyelement', prosrc => 'window_prev' },
+{ oid => '6123', descr => 'next value',
+ proname => 'next', provolatile => 's', prorettype => 'anyelement',
+ proargtypes => 'anyelement', prosrc => 'window_next' },
# functions for range types
{ oid => '3832', descr => 'I/O',
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 108d69ba28..28d098b1cf 100644
--- a/src/include/nodes/execnodes.h
+++ b/src/include/nodes/execnodes.h
@@ -2470,6 +2470,11 @@ typedef enum WindowAggStatus
* tuples during spool */
} WindowAggStatus;
+#define RF_NOT_DETERMINED 0
+#define RF_FRAME_HEAD 1
+#define RF_SKIPPED 2
+#define RF_UNMATCHED 3
+
typedef struct WindowAggState
{
ScanState ss; /* its first field is NodeTag */
@@ -2518,6 +2523,15 @@ typedef struct WindowAggState
int64 groupheadpos; /* current row's peer group head position */
int64 grouptailpos; /* " " " " tail position (group end+1) */
+ /* these fields are used in Row pattern recognition: */
+ RPSkipTo rpSkipTo; /* Row Pattern Skip To type */
+ List *patternVariableList; /* list of row pattern variables names (list of String) */
+ List *patternRegexpList; /* list of row pattern regular expressions ('+' or ''. list of String) */
+ List *defineVariableList; /* list of row pattern definition variables (list of String) */
+ List *defineClauseList; /* expression for row pattern definition
+ * search conditions ExprState list */
+ List *defineInitial; /* list of row pattern definition variable initials (list of String) */
+
MemoryContext partcontext; /* context for partition-lifespan data */
MemoryContext aggcontext; /* shared context for aggregate working data */
MemoryContext curaggcontext; /* current aggregate's working data */
@@ -2554,6 +2568,18 @@ typedef struct WindowAggState
TupleTableSlot *agg_row_slot;
TupleTableSlot *temp_slot_1;
TupleTableSlot *temp_slot_2;
+
+ /* temporary slots for RPR */
+ TupleTableSlot *prev_slot; /* PREV row navigation operator */
+ TupleTableSlot *next_slot; /* NEXT row navigation operator */
+ TupleTableSlot *null_slot; /* all NULL slot */
+
+ /*
+ * Each byte corresponds to a row positioned at absolute its pos in
+ * partition. See above definition for RF_*
+ */
+ char *reduced_frame_map;
+ int64 alloc_sz; /* size of the map */
} WindowAggState;
/* ----------------
--
2.25.1
----Next_Part(Sun_Oct_22_11_39_20_2023_140)--
Content-Type: Text/X-Patch; charset=us-ascii
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
filename="v10-0005-Row-pattern-recognition-patch-docs.patch"
^ permalink raw reply [nested|flat] 8+ messages in thread
* Crash related to Shared Memory
@ 2026-02-15 08:53 Reshmithaa <[email protected]>
0 siblings, 1 reply; 8+ messages in thread
From: Reshmithaa @ 2026-02-15 08:53 UTC (permalink / raw)
To: pgsql-hackers
Hi,
We have developed a PostgreSQL extension and are currently encountering intermittent crashes related to shared memory on PostgreSQL 17.7. The issue does not occur everytime, and we have not been able to reliably reproduce it in our local environment. We have attached the relevant pg logs and backtraces below for reference.
We also noticed a recent commit addressing a DSM-related issue:
https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=1d0fc2499
Could you please confirm whether this change can resolve the type of crash we are encountering?
Thanks & Regards,
Reshmithaa B
Member Technical Staff
ZOHO Corporation
[2136038]:ERROR: XX000: dsa_area could not attach to a segment that has been freed
[2136038]:LOCATION: get_segment_by_index, dsa.c:1781
[2136037]:ERROR: XX000: dsa_area could not attach to a segment that has been freed
[2136037]:LOCATION: get_segment_by_index, dsa.c:1781
[2018946]:ERROR: XX000: dsa_area could not attach to a segment that has been freed
[2018946]:CONTEXT: parallel worker
[2018946]:LOCATION: get_segment_by_index, dsa.c:1781
[2018946]:STATEMENT: select sum(enumrowcount)::bigint from <table> where dbid = <dbid> and table_id != <table_id>
[875575]:LOG: 00000: background worker "parallel worker" (PID 2136037) exited with exit code 1
[875575]:LOCATION: LogChildExit, postmaster.c:3086
[875575]:LOG: 00000: background worker "parallel worker" (PID 2136038) exited with exit code 1
[875575]:LOCATION: LogChildExit, postmaster.c:3086
[2061697]:LOG: 00000: Running single-threaded autovacuum for table <table_id> in database <dbid>
[2061697]:LOCATION: operator(), cstore_vacuum.cpp:267
[875575]:LOG: 00000: server process (PID 2037344) was terminated by signal 11: Segmentation fault
[875575]:DETAIL: Failed process was running: INSERT INTO <tab>...
[568111]:ERROR: 53200: out of memory
[568111]:DETAIL: Failed on DSA request of size 48.
[568111]:LOCATION: dsa_allocate_extended, dsa.c:811
[568111]:STATEMENT: TRUNCATE TABLE tab3
[495070]:LOG: 00000: Running single-threaded autovacuum for table 269613858 in database 17266
[495070]:LOCATION: operator(), cstore_vacuum.cpp:267
[568804]:ERROR: 53200: out of memory
[568804]:DETAIL: Failed while allocating entry 2/17266/55068384.
[568804]:LOCATION: pgstat_get_entry_ref, pgstat_shmem.c:510
[568804]:STATEMENT: ANALYZE tab2_temp
[568920]:ERROR: 53200: out of memory
[568920]:DETAIL: Failed on DSA request of size 48.
[568920]:LOCATION: dsa_allocate_extended, dsa.c:811
[568920]:STATEMENT: ANALYZE tab1
[568804]:ERROR: 25P02: current transaction is aborted, commands ignored until end of transaction block
[568804]:LOCATION: exec_parse_message, postgres.c:1506
[568804]:STATEMENT: delete from tab2 where __ZDBID
in (select __ROWID from tab2_temp)
[568920]:ERROR: 25P02: current transaction is aborted, commands ignored until end of transaction block
[568920]:LOCATION: exec_parse_message, postgres.c:1506
[568920]:STATEMENT: delete from tab4 where __ZDBID
in (select __ROWID from tab1)
[568111]:ERROR: 53200: out of memory
[568111]:DETAIL: Failed on DSA request of size 48.
[568111]:LOCATION: dsa_allocate_extended, dsa.c:811
[568111]:STATEMENT: select TABLE_ID from Table where TABLE_ID=<id>
[875575]:LOG: 00000: server process (PID 568804) was terminated by signal 11: Segmentation fault
[875575]:DETAIL: Failed process was running: ROLLBACK
[875575]:LOCATION: LogChildExit, postmaster.c:3108
[875575]:LOG: 00000: terminating any other active server processes
[875575]:LOCATION: HandleChildCrash, postmaster.c:2897
Attachments:
[text/plain] Trace2.txt (1.2K, ../../[email protected]/3-Trace2.txt)
download | inline:
[2136038]:ERROR: XX000: dsa_area could not attach to a segment that has been freed
[2136038]:LOCATION: get_segment_by_index, dsa.c:1781
[2136037]:ERROR: XX000: dsa_area could not attach to a segment that has been freed
[2136037]:LOCATION: get_segment_by_index, dsa.c:1781
[2018946]:ERROR: XX000: dsa_area could not attach to a segment that has been freed
[2018946]:CONTEXT: parallel worker
[2018946]:LOCATION: get_segment_by_index, dsa.c:1781
[2018946]:STATEMENT: select sum(enumrowcount)::bigint from <table> where dbid = <dbid> and table_id != <table_id>
[875575]:LOG: 00000: background worker "parallel worker" (PID 2136037) exited with exit code 1
[875575]:LOCATION: LogChildExit, postmaster.c:3086
[875575]:LOG: 00000: background worker "parallel worker" (PID 2136038) exited with exit code 1
[875575]:LOCATION: LogChildExit, postmaster.c:3086
[2061697]:LOG: 00000: Running single-threaded autovacuum for table <table_id> in database <dbid>
[2061697]:LOCATION: operator(), cstore_vacuum.cpp:267
[875575]:LOG: 00000: server process (PID 2037344) was terminated by signal 11: Segmentation fault
[875575]:DETAIL: Failed process was running: INSERT INTO <tab>...
[text/plain] Trace1.txt (1.7K, ../../[email protected]/4-Trace1.txt)
download | inline:
[568111]:ERROR: 53200: out of memory
[568111]:DETAIL: Failed on DSA request of size 48.
[568111]:LOCATION: dsa_allocate_extended, dsa.c:811
[568111]:STATEMENT: TRUNCATE TABLE tab3
[495070]:LOG: 00000: Running single-threaded autovacuum for table 269613858 in database 17266
[495070]:LOCATION: operator(), cstore_vacuum.cpp:267
[568804]:ERROR: 53200: out of memory
[568804]:DETAIL: Failed while allocating entry 2/17266/55068384.
[568804]:LOCATION: pgstat_get_entry_ref, pgstat_shmem.c:510
[568804]:STATEMENT: ANALYZE tab2_temp
[568920]:ERROR: 53200: out of memory
[568920]:DETAIL: Failed on DSA request of size 48.
[568920]:LOCATION: dsa_allocate_extended, dsa.c:811
[568920]:STATEMENT: ANALYZE tab1
[568804]:ERROR: 25P02: current transaction is aborted, commands ignored until end of transaction block
[568804]:LOCATION: exec_parse_message, postgres.c:1506
[568804]:STATEMENT: delete from tab2 where __ZDBID
in (select __ROWID from tab2_temp)
[568920]:ERROR: 25P02: current transaction is aborted, commands ignored until end of transaction block
[568920]:LOCATION: exec_parse_message, postgres.c:1506
[568920]:STATEMENT: delete from tab4 where __ZDBID
in (select __ROWID from tab1)
[568111]:ERROR: 53200: out of memory
[568111]:DETAIL: Failed on DSA request of size 48.
[568111]:LOCATION: dsa_allocate_extended, dsa.c:811
[568111]:STATEMENT: select TABLE_ID from Table where TABLE_ID=<id>
[875575]:LOG: 00000: server process (PID 568804) was terminated by signal 11: Segmentation fault
[875575]:DETAIL: Failed process was running: ROLLBACK
[875575]:LOCATION: LogChildExit, postmaster.c:3108
[875575]:LOG: 00000: terminating any other active server processes
[875575]:LOCATION: HandleChildCrash, postmaster.c:2897
^ permalink raw reply [nested|flat] 8+ messages in thread
* Re: Crash related to Shared Memory
@ 2026-02-15 22:04 Tomas Vondra <[email protected]>
parent: Reshmithaa <[email protected]>
0 siblings, 1 reply; 8+ messages in thread
From: Tomas Vondra @ 2026-02-15 22:04 UTC (permalink / raw)
To: Reshmithaa <[email protected]>; pgsql-hackers
Hi,
On 2/15/26 09:53, Reshmithaa wrote:
> Hi,
>
> We have developed a PostgreSQL extension and are currently encountering
> intermittent crashes related to shared memory on PostgreSQL 17.7. The
> issue does not occur everytime, and we have not been able to reliably
> reproduce it in our local environment. We have attached the relevant pg
> logs and backtraces below for reference.
>
> We also noticed a recent commit addressing a DSM-related issue:
>
> https://git.postgresql.org/gitweb/?
> p=postgresql.git;a=commitdiff;h=1d0fc2499 <https://git.postgresql.org/
> gitweb/?p=postgresql.git;a=commitdiff;h=1d0fc2499>
>
> Could you please confirm whether this change can resolve the type of
> crash we are encountering?
>
Maybe, but it's hard to say based on the logs you provided.
In the commit message you linked, Robert speculated this should not be
happening in core Postgres, but that maybe extensions could trip over
this. What extensions are you using? Especially extensions third-party
extensions?
It's interesting both traces end with a segfault, but in both cases
there are "strange" errors immediately before that. In particular the
first trace shows
[568804]:ERROR: 53200: out of memory
[568804]:DETAIL: Failed while allocating entry 2/17266/55068384.
[568804]:LOCATION: pgstat_get_entry_ref, pgstat_shmem.c:510
[568804]:STATEMENT: ANALYZE tab2_temp
For the process that then crashes with a segfault. The second trace
unfortunately does not show what happened to PID 2037344 before it
crashes, which would be very interesting to know. Was it an OOM too?
But there are a couple other suspicious errors from other PIDs, like
[2136038]:ERROR: XX000: dsa_area could not attach to a segment that has
been freed
[2136038]:LOCATION: get_segment_by_index, dsa.c:1781
I don't think this should be happening in core code, at least I don't
recall seeing anything like that recently.
I wonder if the cleanup after OOM could lead to the crash because the
error cleanup destroys the short-lived context, in a way Robert did not
envision in the commit message. But I haven't tried and it's just a
speculation.
FWIW even if the commit (and upgrading to 17.8) fixes the crash, I don't
think that'll fix the other errors shown in the traces. You should
probably look into that.
regards
--
Tomas Vondra
^ permalink raw reply [nested|flat] 8+ messages in thread
* Re: Crash related to Shared Memory
@ 2026-02-16 08:42 Reshmithaa <[email protected]>
parent: Tomas Vondra <[email protected]>
0 siblings, 2 replies; 8+ messages in thread
From: Reshmithaa @ 2026-02-16 08:42 UTC (permalink / raw)
To: [email protected]; +Cc: pgsql-hackers
Hi Tomas Vondra,
> What extensions are you using? Especially extensions third-party
> extensions?
We are working on our own columnar extension and have modified the PostgreSQL source code to enable pg stats for foreign tables and to support autoanalyze and autovacuum on foreign tables.
From PostgreSQL 15 onward, statistics were moved to shared memory. We started observing this issue in production after upgrading from PostgreSQL 14 to PostgreSQL 17.2 / 17.7.
Could this dsa issue be related to pg stats?
> The second trace
> unfortunately does not show what happened to PID 2037344 before it
> crashes, which would be very interesting to know. Was it an OOM too?
The process with PID 2037344 did not terminate due to an OOM intead ended with segfalut.
Regards
Reshmithaa B
From: Tomas Vondra < mailto:[email protected] >
To: "Reshmithaa"< mailto:[email protected] >, "pgsql-hackers"< mailto:[email protected] >
Date: Mon, 16 Feb 2026 03:34:53 +0530
Subject: Re: Crash related to Shared Memory
Hi,
On 2/15/26 09:53, Reshmithaa wrote:
> Hi,
>
> We have developed a PostgreSQL extension and are currently encountering
> intermittent crashes related to shared memory on PostgreSQL 17.7. The
> issue does not occur everytime, and we have not been able to reliably
> reproduce it in our local environment. We have attached the relevant pg
> logs and backtraces below for reference.
>
> We also noticed a recent commit addressing a DSM-related issue:
>
> https://git.postgresql.org/gitweb/?
> p=postgresql.git;a=commitdiff;h=1d0fc2499 < https://git.postgresql.org/
> gitweb/?p=postgresql.git;a=commitdiff;h=1d0fc2499>
>
> Could you please confirm whether this change can resolve the type of
> crash we are encountering?
>
Maybe, but it's hard to say based on the logs you provided.
In the commit message you linked, Robert speculated this should not be
happening in core Postgres, but that maybe extensions could trip over
this. What extensions are you using? Especially extensions third-party
extensions?
It's interesting both traces end with a segfault, but in both cases
there are "strange" errors immediately before that. In particular the
first trace shows
[568804]:ERROR: 53200: out of memory
[568804]:DETAIL: Failed while allocating entry 2/17266/55068384.
[568804]:LOCATION: pgstat_get_entry_ref, pgstat_shmem.c:510
[568804]:STATEMENT: ANALYZE tab2_temp
For the process that then crashes with a segfault. The second trace
unfortunately does not show what happened to PID 2037344 before it
crashes, which would be very interesting to know. Was it an OOM too?
But there are a couple other suspicious errors from other PIDs, like
[2136038]:ERROR: XX000: dsa_area could not attach to a segment that has
been freed
[2136038]:LOCATION: get_segment_by_index, dsa.c:1781
I don't think this should be happening in core code, at least I don't
recall seeing anything like that recently.
I wonder if the cleanup after OOM could lead to the crash because the
error cleanup destroys the short-lived context, in a way Robert did not
envision in the commit message. But I haven't tried and it's just a
speculation.
FWIW even if the commit (and upgrading to 17.8) fixes the crash, I don't
think that'll fix the other errors shown in the traces. You should
probably look into that.
regards
--
Tomas Vondra
^ permalink raw reply [nested|flat] 8+ messages in thread
* Re: Crash related to Shared Memory
@ 2026-02-16 09:17 Reshmithaa <[email protected]>
parent: Reshmithaa <[email protected]>
1 sibling, 1 reply; 8+ messages in thread
From: Reshmithaa @ 2026-02-16 09:17 UTC (permalink / raw)
To: Tomas <[email protected]>; +Cc: pgsql-hackers
Hi,
> The second trace
> unfortunately does not show what happened to PID 2037344 before it
> crashes, which would be very interesting to know. Was it an OOM too?
Kindly find the attachment below.
Regards,
Reshmithaa B
From: Reshmithaa <[email protected]>
To: <[email protected]>
Cc: <[email protected]>
Date: Mon, 16 Feb 2026 14:12:25 +0530
Subject: Re: Crash related to Shared Memory
Hi Tomas Vondra,
> What extensions are you using? Especially extensions third-party
> extensions?
We are working on our own columnar extension and have modified the PostgreSQL source code to enable pg stats for foreign tables and to support autoanalyze and autovacuum on foreign tables.
From PostgreSQL 15 onward, statistics were moved to shared memory. We started observing this issue in production after upgrading from PostgreSQL 14 to PostgreSQL 17.2 / 17.7.
Could this dsa issue be related to pg stats?
> The second trace
> unfortunately does not show what happened to PID 2037344 before it
> crashes, which would be very interesting to know. Was it an OOM too?
The process with PID 2037344 did not terminate due to an OOM intead ended with segfalut.
Regards
Reshmithaa B
From: Tomas Vondra < mailto:[email protected] >
To: "Reshmithaa"< mailto:[email protected] >, "pgsql-hackers"< mailto:[email protected] >
Date: Mon, 16 Feb 2026 03:34:53 +0530
Subject: Re: Crash related to Shared Memory
Hi,
On 2/15/26 09:53, Reshmithaa wrote:
> Hi,
>
> We have developed a PostgreSQL extension and are currently encountering
> intermittent crashes related to shared memory on PostgreSQL 17.7. The
> issue does not occur everytime, and we have not been able to reliably
> reproduce it in our local environment. We have attached the relevant pg
> logs and backtraces below for reference.
>
> We also noticed a recent commit addressing a DSM-related issue:
>
> https://git.postgresql.org/gitweb/?
> p=postgresql.git;a=commitdiff;h=1d0fc2499 < https://git.postgresql.org/
> gitweb/?p=postgresql.git;a=commitdiff;h=1d0fc2499>
>
> Could you please confirm whether this change can resolve the type of
> crash we are encountering?
>
Maybe, but it's hard to say based on the logs you provided.
In the commit message you linked, Robert speculated this should not be
happening in core Postgres, but that maybe extensions could trip over
this. What extensions are you using? Especially extensions third-party
extensions?
It's interesting both traces end with a segfault, but in both cases
there are "strange" errors immediately before that. In particular the
first trace shows
[568804]:ERROR: 53200: out of memory
[568804]:DETAIL: Failed while allocating entry 2/17266/55068384.
[568804]:LOCATION: pgstat_get_entry_ref, pgstat_shmem.c:510
[568804]:STATEMENT: ANALYZE tab2_temp
For the process that then crashes with a segfault. The second trace
unfortunately does not show what happened to PID 2037344 before it
crashes, which would be very interesting to know. Was it an OOM too?
But there are a couple other suspicious errors from other PIDs, like
[2136038]:ERROR: XX000: dsa_area could not attach to a segment that has
been freed
[2136038]:LOCATION: get_segment_by_index, dsa.c:1781
I don't think this should be happening in core code, at least I don't
recall seeing anything like that recently.
I wonder if the cleanup after OOM could lead to the crash because the
error cleanup destroys the short-lived context, in a way Robert did not
envision in the commit message. But I haven't tried and it's just a
speculation.
FWIW even if the commit (and upgrading to 17.8) fixes the crash, I don't
think that'll fix the other errors shown in the traces. You should
probably look into that.
regards
--
Tomas Vondra
2026-01-22 00:57:51 GMT:<ip>(33028)[2037344]:LOG: 00000: PRIMITIVE NOT USED: map_pg_backend_pid
2026-01-22 00:57:51 GMT:<ip>(33028)[2037344]:LOCATION: LogPrimFunctions, primitiveMgr.cpp:39
2026-01-22 00:57:51 GMT:<ip>(33028)[2037344]:STATEMENT: select pg_backend_pid()
2026-01-22 00:57:51 GMT:<ip>(33028)[2037344]:LOG: 00000: PRIMITIVE NOT USED: map_pg_backend_pid
2026-01-22 00:57:51 GMT:<ip>(33028)[2037344]:LOCATION: LogPrimFunctions, primitiveMgr.cpp:39
2026-01-22 00:57:51 GMT:<ip>(33028)[2037344]:STATEMENT: select pg_backend_pid()
2026-01-22 00:57:51 GMT::@:[2061697]:LOG: 00000: Running single-threaded autovacuum for table 261184335 in database 17266
2026-01-22 00:57:51 GMT::@:[2061697]:LOCATION: operator(), cstore_vacuum.cpp:267
2026-01-22 00:57:51 GMT::@:[2061905]:LOG: 00000: Running single-threaded autovacuum for table 193649 in database 17266
2026-01-22 00:57:51 GMT::@:[2061905]:LOCATION: operator(), cstore_vacuum.cpp:267
2026-01-22 00:57:51 GMT:<ip>(34946)[2126874]:LOG: 00000: PRIMITIVE NOT USED: map_pg_backend_pid
2026-01-22 00:57:51 GMT:<ip>(34946)[2126874]:LOCATION: LogPrimFunctions, primitiveMgr.cpp:39
2026-01-22 00:57:51 GMT:<ip>(34946)[2126874]:STATEMENT: select pg_backend_pid(),'value1','value2'
2026-01-22 00:57:51 GMT:<ip>(33028)[2037344]:LOG: 00000: PRIMITIVE NOT USED: map_pg_backend_pid
2026-01-22 00:57:51 GMT:<ip>(33028)[2037344]:LOCATION: LogPrimFunctions, primitiveMgr.cpp:39
2026-01-22 00:57:51 GMT:<ip>(33028)[2037344]:STATEMENT: select pg_backend_pid(),'value1','value2'
2026-01-22 00:57:51 GMT::@:[2061697]:LOG: 00000: Running single-threaded autovacuum for table 261218586 in database 17266
2026-01-22 00:57:51 GMT::@:[2061697]:LOCATION: operator(), cstore_vacuum.cpp:267
2026-01-22 00:57:51 GMT::@:[2061697]:LOG: 00000: Running single-threaded autovacuum for table 261222200 in database 17266
2026-01-22 00:57:51 GMT::@:[2061697]:LOCATION: operator(), cstore_vacuum.cpp:267
2026-01-22 00:57:51 GMT::@:[2136038]:ERROR: XX000: dsa_area could not attach to a segment that has been freed
2026-01-22 00:57:51 GMT::@:[2136038]:LOCATION: get_segment_by_index, dsa.c:1781
2026-01-22 00:57:51 GMT::@:[2136037]:ERROR: XX000: dsa_area could not attach to a segment that has been freed
2026-01-22 00:57:51 GMT::@:[2136037]:LOCATION: get_segment_by_index, dsa.c:1781
2026-01-22 00:57:51 GMT:<ip>(46398)[2018946]:ERROR: XX000: dsa_area could not attach to a segment that has been freed
2026-01-22 00:57:51 GMT:<ip>(46398)[2018946]:CONTEXT: parallel worker
2026-01-22 00:57:51 GMT:<ip>(46398)[2018946]:LOCATION: get_segment_by_index, dsa.c:1781
2026-01-22 00:57:51 GMT:<ip>(46398)[2018946]:STATEMENT: select sum(enumrowcount)::bigint from srlaudit where dbid = <id> and table_id != <value>
2026-01-22 00:57:51 GMT::@:[875575]:LOG: 00000: background worker "parallel worker" (PID 2136037) exited with exit code 1
2026-01-22 00:57:51 GMT::@:[875575]:LOCATION: LogChildExit, postmaster.c:3086
2026-01-22 00:57:51 GMT::@:[875575]:LOG: 00000: background worker "parallel worker" (PID 2136038) exited with exit code 1
2026-01-22 00:57:51 GMT::@:[875575]:LOCATION: LogChildExit, postmaster.c:3086
2026-01-22 00:57:51 GMT::@:[2061697]:LOG: 00000: Running single-threaded autovacuum for table 129145779 in database 17266
2026-01-22 00:57:51 GMT::@:[2061697]:LOCATION: operator(), cstore_vacuum.cpp:267
2026-01-22 00:57:51 GMT::@:[875575]:LOG: 00000: server process (PID 2037344) was terminated by signal 11: Segmentation fault
2026-01-22 00:57:51 GMT::@:[875575]:DETAIL: Failed process was running: INSERT INTO tab (c1, c2, c3, c3, c4, c5, c6, c7, c8, c9, c10, c11, c12, c13)...
2026-01-22 00:57:51 GMT::@:[875575]:LOCATION: LogChildExit, postmaster.c:3108
2026-01-22 00:57:51 GMT::@:[875575]:LOG: 00000: terminating any other active server processes
2026-01-22 00:57:51 GMT::@:[875575]:LOCATION: HandleChildCrash, postmaster.c:2897
2026-01-22 00:57:52 GMT:172.25.249.16(59040):sas@reports:[2136093]:FATAL: 57P03: the database system is in recovery mode
2026-01-22 00:57:52 GMT:172.25.249.16(59040):sas@reports:[2136093]:LOCATION: BackendInitialize, backend_startup.c:299
2026-01-22 00:57:52 GMT:172.25.249.16(59054):sas@reports:[2136094]:FATAL: 57P03: the database system is in recovery mode
Attachments:
[text/plain] Trace2.txt (4.2K, ../../[email protected]/3-Trace2.txt)
download | inline:
2026-01-22 00:57:51 GMT:<ip>(33028)[2037344]:LOG: 00000: PRIMITIVE NOT USED: map_pg_backend_pid
2026-01-22 00:57:51 GMT:<ip>(33028)[2037344]:LOCATION: LogPrimFunctions, primitiveMgr.cpp:39
2026-01-22 00:57:51 GMT:<ip>(33028)[2037344]:STATEMENT: select pg_backend_pid()
2026-01-22 00:57:51 GMT:<ip>(33028)[2037344]:LOG: 00000: PRIMITIVE NOT USED: map_pg_backend_pid
2026-01-22 00:57:51 GMT:<ip>(33028)[2037344]:LOCATION: LogPrimFunctions, primitiveMgr.cpp:39
2026-01-22 00:57:51 GMT:<ip>(33028)[2037344]:STATEMENT: select pg_backend_pid()
2026-01-22 00:57:51 GMT::@:[2061697]:LOG: 00000: Running single-threaded autovacuum for table 261184335 in database 17266
2026-01-22 00:57:51 GMT::@:[2061697]:LOCATION: operator(), cstore_vacuum.cpp:267
2026-01-22 00:57:51 GMT::@:[2061905]:LOG: 00000: Running single-threaded autovacuum for table 193649 in database 17266
2026-01-22 00:57:51 GMT::@:[2061905]:LOCATION: operator(), cstore_vacuum.cpp:267
2026-01-22 00:57:51 GMT:<ip>(34946)[2126874]:LOG: 00000: PRIMITIVE NOT USED: map_pg_backend_pid
2026-01-22 00:57:51 GMT:<ip>(34946)[2126874]:LOCATION: LogPrimFunctions, primitiveMgr.cpp:39
2026-01-22 00:57:51 GMT:<ip>(34946)[2126874]:STATEMENT: select pg_backend_pid(),'value1','value2'
2026-01-22 00:57:51 GMT:<ip>(33028)[2037344]:LOG: 00000: PRIMITIVE NOT USED: map_pg_backend_pid
2026-01-22 00:57:51 GMT:<ip>(33028)[2037344]:LOCATION: LogPrimFunctions, primitiveMgr.cpp:39
2026-01-22 00:57:51 GMT:<ip>(33028)[2037344]:STATEMENT: select pg_backend_pid(),'value1','value2'
2026-01-22 00:57:51 GMT::@:[2061697]:LOG: 00000: Running single-threaded autovacuum for table 261218586 in database 17266
2026-01-22 00:57:51 GMT::@:[2061697]:LOCATION: operator(), cstore_vacuum.cpp:267
2026-01-22 00:57:51 GMT::@:[2061697]:LOG: 00000: Running single-threaded autovacuum for table 261222200 in database 17266
2026-01-22 00:57:51 GMT::@:[2061697]:LOCATION: operator(), cstore_vacuum.cpp:267
2026-01-22 00:57:51 GMT::@:[2136038]:ERROR: XX000: dsa_area could not attach to a segment that has been freed
2026-01-22 00:57:51 GMT::@:[2136038]:LOCATION: get_segment_by_index, dsa.c:1781
2026-01-22 00:57:51 GMT::@:[2136037]:ERROR: XX000: dsa_area could not attach to a segment that has been freed
2026-01-22 00:57:51 GMT::@:[2136037]:LOCATION: get_segment_by_index, dsa.c:1781
2026-01-22 00:57:51 GMT:<ip>(46398)[2018946]:ERROR: XX000: dsa_area could not attach to a segment that has been freed
2026-01-22 00:57:51 GMT:<ip>(46398)[2018946]:CONTEXT: parallel worker
2026-01-22 00:57:51 GMT:<ip>(46398)[2018946]:LOCATION: get_segment_by_index, dsa.c:1781
2026-01-22 00:57:51 GMT:<ip>(46398)[2018946]:STATEMENT: select sum(enumrowcount)::bigint from srlaudit where dbid = <id> and table_id != <value>
2026-01-22 00:57:51 GMT::@:[875575]:LOG: 00000: background worker "parallel worker" (PID 2136037) exited with exit code 1
2026-01-22 00:57:51 GMT::@:[875575]:LOCATION: LogChildExit, postmaster.c:3086
2026-01-22 00:57:51 GMT::@:[875575]:LOG: 00000: background worker "parallel worker" (PID 2136038) exited with exit code 1
2026-01-22 00:57:51 GMT::@:[875575]:LOCATION: LogChildExit, postmaster.c:3086
2026-01-22 00:57:51 GMT::@:[2061697]:LOG: 00000: Running single-threaded autovacuum for table 129145779 in database 17266
2026-01-22 00:57:51 GMT::@:[2061697]:LOCATION: operator(), cstore_vacuum.cpp:267
2026-01-22 00:57:51 GMT::@:[875575]:LOG: 00000: server process (PID 2037344) was terminated by signal 11: Segmentation fault
2026-01-22 00:57:51 GMT::@:[875575]:DETAIL: Failed process was running: INSERT INTO tab (c1, c2, c3, c3, c4, c5, c6, c7, c8, c9, c10, c11, c12, c13)...
2026-01-22 00:57:51 GMT::@:[875575]:LOCATION: LogChildExit, postmaster.c:3108
2026-01-22 00:57:51 GMT::@:[875575]:LOG: 00000: terminating any other active server processes
2026-01-22 00:57:51 GMT::@:[875575]:LOCATION: HandleChildCrash, postmaster.c:2897
2026-01-22 00:57:52 GMT:172.25.249.16(59040):sas@reports:[2136093]:FATAL: 57P03: the database system is in recovery mode
2026-01-22 00:57:52 GMT:172.25.249.16(59040):sas@reports:[2136093]:LOCATION: BackendInitialize, backend_startup.c:299
2026-01-22 00:57:52 GMT:172.25.249.16(59054):sas@reports:[2136094]:FATAL: 57P03: the database system is in recovery mode
^ permalink raw reply [nested|flat] 8+ messages in thread
* Re: Crash related to Shared Memory
@ 2026-02-16 10:42 Tomas Vondra <[email protected]>
parent: Reshmithaa <[email protected]>
1 sibling, 0 replies; 8+ messages in thread
From: Tomas Vondra @ 2026-02-16 10:42 UTC (permalink / raw)
To: Reshmithaa <[email protected]>; +Cc: pgsql-hackers
On 2/16/26 09:42, Reshmithaa wrote:
> Hi Tomas Vondra,
>
>> What extensions are you using? Especially extensions third-party
>
>> extensions?
>
> We are working on our own columnar extension and have modified the
> PostgreSQL source code to enable pg stats for foreign tables and to
> support autoanalyze and autovacuum on foreign tables.
>
Then it matches the explanation in Robert's commit message. Chances are
that commit will solve the crash, but the other errors in your traces
are likely to remain.
> From PostgreSQL 15 onward, statistics were moved to shared memory. We
> started observing this issue in production after upgrading from
> PostgreSQL 14 to PostgreSQL 17.2 / 17.7.
>
> Could this dsa issue be related to pg stats?
>
You literally have the traces full of error messages like this:
[568804]:ERROR: 53200: out of memory
[568804]:DETAIL: Failed while allocating entry 2/17266/55068384.
[568804]:LOCATION: pgstat_get_entry_ref, pgstat_shmem.c:510
[568804]:STATEMENT: ANALYZE tab2_temp
That's clearly related to pgstat. My bet is that's a bug in your
extension, not sure where.
>
>> The second trace
>
>> unfortunately does not show what happened to PID 2037344 before it
>
>> crashes, which would be very interesting to know. Was it an OOM too?
>
> The process with PID 2037344 did not terminate due to an OOM intead
> ended with segfalut.
>
The question is what happened to the process before it segfaults.
cheers
--
Tomas Vondra
^ permalink raw reply [nested|flat] 8+ messages in thread
* Re: Crash related to Shared Memory
@ 2026-02-16 10:43 Tomas Vondra <[email protected]>
parent: Reshmithaa <[email protected]>
0 siblings, 1 reply; 8+ messages in thread
From: Tomas Vondra @ 2026-02-16 10:43 UTC (permalink / raw)
To: Reshmithaa <[email protected]>; +Cc: pgsql-hackers
On 2/16/26 10:17, Reshmithaa wrote:
> Hi,
>
> > The second trace
>
> > unfortunately does not show what happened to PID 2037344 before it
>
> > crashes, which would be very interesting to know. Was it an OOM too?
>
> Kindly find the attachment below.
>
I have no idea what
LOG: 00000: PRIMITIVE NOT USED: map_pg_backend_pid
LOCATION: LogPrimFunctions, primitiveMgr.cpp:39
STATEMENT: select pg_backend_pid()
means, that's clearly something in your fork/extension.
regards
--
Tomas Vondra
^ permalink raw reply [nested|flat] 8+ messages in thread
* Re: Crash related to Shared Memory
@ 2026-02-16 11:54 Reshmithaa <[email protected]>
parent: Tomas Vondra <[email protected]>
0 siblings, 0 replies; 8+ messages in thread
From: Reshmithaa @ 2026-02-16 11:54 UTC (permalink / raw)
To: Tomas Vondra <[email protected]>; +Cc: pgsql-hackers
Hi,
Thanks for your reply, we will look into it.
Regards,
Reshmithaa B
From: Tomas Vondra <[email protected]>
To: "Reshmithaa"<[email protected]>
Cc: "pgsql-hackers"<[email protected]>
Date: Mon, 16 Feb 2026 16:13:07 +0530
Subject: Re: Crash related to Shared Memory
On 2/16/26 10:17, Reshmithaa wrote:
> Hi,
>
> > The second trace
>
> > unfortunately does not show what happened to PID 2037344 before it
>
> > crashes, which would be very interesting to know. Was it an OOM too?
>
> Kindly find the attachment below.
>
I have no idea what
LOG: 00000: PRIMITIVE NOT USED: map_pg_backend_pid
LOCATION: LogPrimFunctions, primitiveMgr.cpp:39
STATEMENT: select pg_backend_pid()
means, that's clearly something in your fork/extension.
regards
--
Tomas Vondra
^ permalink raw reply [nested|flat] 8+ messages in thread
end of thread, other threads:[~2026-02-16 11:54 UTC | newest]
Thread overview: 8+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2023-10-22 02:22 [PATCH v10 4/7] Row pattern recognition patch (executor). Tatsuo Ishii <[email protected]>
2026-02-15 08:53 Crash related to Shared Memory Reshmithaa <[email protected]>
2026-02-15 22:04 ` Re: Crash related to Shared Memory Tomas Vondra <[email protected]>
2026-02-16 08:42 ` Re: Crash related to Shared Memory Reshmithaa <[email protected]>
2026-02-16 09:17 ` Re: Crash related to Shared Memory Reshmithaa <[email protected]>
2026-02-16 10:43 ` Re: Crash related to Shared Memory Tomas Vondra <[email protected]>
2026-02-16 11:54 ` Re: Crash related to Shared Memory Reshmithaa <[email protected]>
2026-02-16 10:42 ` Re: Crash related to Shared Memory Tomas Vondra <[email protected]>
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