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[PATCH v4] Do not use RelationNeedsWAL to identify relation persistence 2+ messages / 2 participants [nested] [flat]
* [PATCH v4] Do not use RelationNeedsWAL to identify relation persistence @ 2021-01-18 05:47 Kyotaro Horiguchi <[email protected]> 0 siblings, 0 replies; 2+ messages in thread From: Kyotaro Horiguchi @ 2021-01-18 05:47 UTC (permalink / raw) RelationNeedsWAL() may return false for a permanent relation when wal_level=minimal and the relation is created or truncated in the current transaction. Directly examine relpersistence instead of using the function to know relation persistence. --- src/backend/catalog/pg_publication.c | 2 +- src/backend/optimizer/util/plancat.c | 3 ++- src/include/storage/bufmgr.h | 8 +++++++- src/include/utils/rel.h | 2 +- src/include/utils/snapmgr.h | 2 +- 5 files changed, 12 insertions(+), 5 deletions(-) diff --git a/src/backend/catalog/pg_publication.c b/src/backend/catalog/pg_publication.c index 5f8e1c64e1..84d2efcfd2 100644 --- a/src/backend/catalog/pg_publication.c +++ b/src/backend/catalog/pg_publication.c @@ -67,7 +67,7 @@ check_publication_add_relation(Relation targetrel) errdetail("System tables cannot be added to publications."))); /* UNLOGGED and TEMP relations cannot be part of publication. */ - if (!RelationNeedsWAL(targetrel)) + if (targetrel->rd_rel->relpersistence != RELPERSISTENCE_PERMANENT) ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("table \"%s\" cannot be replicated", diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c index da322b453e..177e6e336a 100644 --- a/src/backend/optimizer/util/plancat.c +++ b/src/backend/optimizer/util/plancat.c @@ -126,7 +126,8 @@ get_relation_info(PlannerInfo *root, Oid relationObjectId, bool inhparent, relation = table_open(relationObjectId, NoLock); /* Temporary and unlogged relations are inaccessible during recovery. */ - if (!RelationNeedsWAL(relation) && RecoveryInProgress()) + if (relation->rd_rel->relpersistence != RELPERSISTENCE_PERMANENT && + RecoveryInProgress()) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("cannot access temporary or unlogged relations during recovery"))); diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h index fb00fda6a7..e641174798 100644 --- a/src/include/storage/bufmgr.h +++ b/src/include/storage/bufmgr.h @@ -14,6 +14,7 @@ #ifndef BUFMGR_H #define BUFMGR_H +#include "access/xlog.h" #include "storage/block.h" #include "storage/buf.h" #include "storage/bufpage.h" @@ -278,12 +279,17 @@ TestForOldSnapshot(Snapshot snapshot, Relation relation, Page page) { Assert(relation != NULL); + /* + * While wal_level=minimal, early pruning can happen without updating page + * LSN. Don't take the fast-return path while wal_level=minimal so that we + * don't miss early pruning. + */ if (old_snapshot_threshold >= 0 && (snapshot) != NULL && ((snapshot)->snapshot_type == SNAPSHOT_MVCC || (snapshot)->snapshot_type == SNAPSHOT_TOAST) && !XLogRecPtrIsInvalid((snapshot)->lsn) - && PageGetLSN(page) > (snapshot)->lsn) + && (!XLogIsNeeded() || PageGetLSN(page) > (snapshot)->lsn)) TestForOldSnapshot_impl(snapshot, relation); } diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h index 10b63982c0..f58d65cf28 100644 --- a/src/include/utils/rel.h +++ b/src/include/utils/rel.h @@ -554,7 +554,7 @@ typedef struct ViewOptions /* * RelationNeedsWAL - * True if relation needs WAL. + * True if relation needs WAL at the time. * * Returns false if wal_level = minimal and this relation is created or * truncated in the current transaction. See "Skipping WAL for New diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index 579be352c5..c21ee3c289 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -37,7 +37,7 @@ */ #define RelationAllowsEarlyPruning(rel) \ ( \ - RelationNeedsWAL(rel) \ + (rel)->rd_rel->relpersistence == RELPERSISTENCE_PERMANENT \ && !IsCatalogRelation(rel) \ && !RelationIsAccessibleInLogicalDecoding(rel) \ ) -- 2.27.0 ----Next_Part(Wed_Jan_20_17_34_44_2021_328)---- ^ permalink raw reply [nested|flat] 2+ messages in thread
* [PATCH v15 6/8] Row pattern recognition patch (docs). @ 2024-03-28 10:30 Tatsuo Ishii <[email protected]> 0 siblings, 0 replies; 2+ messages in thread From: Tatsuo Ishii @ 2024-03-28 10:30 UTC (permalink / raw) --- doc/src/sgml/advanced.sgml | 80 ++++++++++++++++++++++++++++++++++++ doc/src/sgml/func.sgml | 54 ++++++++++++++++++++++++ doc/src/sgml/ref/select.sgml | 38 ++++++++++++++++- 3 files changed, 170 insertions(+), 2 deletions(-) diff --git a/doc/src/sgml/advanced.sgml b/doc/src/sgml/advanced.sgml index 755c9f1485..cf18dd887e 100644 --- a/doc/src/sgml/advanced.sgml +++ b/doc/src/sgml/advanced.sgml @@ -537,6 +537,86 @@ WHERE pos < 3; <literal>rank</literal> less than 3. </para> + <para> + Row pattern common syntax can be used to perform row pattern recognition + in a query. Row pattern common syntax includes two sub + clauses: <literal>DEFINE</literal> + and <literal>PATTERN</literal>. <literal>DEFINE</literal> defines + definition variables along with an expression. The expression must be a + logical expression, which means it must + return <literal>TRUE</literal>, <literal>FALSE</literal> + or <literal>NULL</literal>. The expression may comprise column references + and functions. Window functions, aggregate functions and subqueries are + not allowed. An example of <literal>DEFINE</literal> is as follows. + +<programlisting> +DEFINE + LOWPRICE AS price <= 100, + UP AS price > PREV(price), + DOWN AS price < PREV(price) +</programlisting> + + Note that <function>PREV</function> returns the price column in the + previous row if it's called in a context of row pattern recognition. So in + the second line the definition variable "UP" is <literal>TRUE</literal> + when the price column in the current row is greater than the price column + in the previous row. Likewise, "DOWN" is <literal>TRUE</literal> when when + the price column in the current row is lower than the price column in the + previous row. + </para> + <para> + Once <literal>DEFINE</literal> exists, <literal>PATTERN</literal> can be + used. <literal>PATTERN</literal> defines a sequence of rows that satisfies + certain conditions. For example following <literal>PATTERN</literal> + defines that a row starts with the condition "LOWPRICE", then one or more + rows satisfy "UP" and finally one or more rows satisfy "DOWN". Note that + "+" means one or more matches. Also you can use "*", which means zero or + more matches. If a sequence of rows which satisfies the PATTERN is found, + in the starting row of the sequence of rows all window functions and + aggregates are shown in the target list. Note that aggregations only look + into the matched rows, rather than whole frame. In the second or + subsequent rows all window functions and aggregates are NULL. For rows + that do not match the PATTERN, all window functions and aggregates are + shown AS NULL too, except count which shows 0. This is because the + unmatched rows are in an empty frame. Example of + a <literal>SELECT</literal> using the <literal>DEFINE</literal> + and <literal>PATTERN</literal> clause is as follows. + +<programlisting> +SELECT company, tdate, price, + first_value(price) OVER w, + max(price) OVER w, + count(price) OVER w +FROM stock, + WINDOW w AS ( + PARTITION BY company + ORDER BY tdate + ROWS BETWEEN CURRENT ROW AND UNBOUNDED FOLLOWING + AFTER MATCH SKIP PAST LAST ROW + INITIAL + PATTERN (LOWPRICE UP+ DOWN+) + DEFINE + LOWPRICE AS price <= 100, + UP AS price > PREV(price), + DOWN AS price < PREV(price) +); +</programlisting> +<screen> + company | tdate | price | first_value | max | count +----------+------------+-------+-------------+-----+------- + company1 | 2023-07-01 | 100 | 100 | 200 | 4 + company1 | 2023-07-02 | 200 | | | + company1 | 2023-07-03 | 150 | | | + company1 | 2023-07-04 | 140 | | | + company1 | 2023-07-05 | 150 | | | 0 + company1 | 2023-07-06 | 90 | 90 | 130 | 4 + company1 | 2023-07-07 | 110 | | | + company1 | 2023-07-08 | 130 | | | + company1 | 2023-07-09 | 120 | | | + company1 | 2023-07-10 | 130 | | | 0 +</screen> + </para> + <para> When a query involves multiple window functions, it is possible to write out each one with a separate <literal>OVER</literal> clause, but this is diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index 93b0bc2bc6..d25eeb3327 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -22637,6 +22637,7 @@ SELECT count(*) FROM sometable; returns <literal>NULL</literal> if there is no such row. </para></entry> </row> + </tbody> </tgroup> </table> @@ -22676,6 +22677,59 @@ SELECT count(*) FROM sometable; Other frame specifications can be used to obtain other effects. </para> + <para> + Row pattern recognition navigation functions are listed in + <xref linkend="functions-rpr-navigation-table"/>. These functions + can be used to describe DEFINE clause of Row pattern recognition. + </para> + + <table id="functions-rpr-navigation-table"> + <title>Row Pattern Navigation Functions</title> + <tgroup cols="1"> + <thead> + <row> + <entry role="func_table_entry"><para role="func_signature"> + Function + </para> + <para> + Description + </para></entry> + </row> + </thead> + + <tbody> + <row> + <entry role="func_table_entry"><para role="func_signature"> + <indexterm> + <primary>prev</primary> + </indexterm> + <function>prev</function> ( <parameter>value</parameter> <type>anyelement</type> ) + <returnvalue>anyelement</returnvalue> + </para> + <para> + Returns the column value at the previous row; + returns NULL if there is no previous row in the window frame. + </para></entry> + </row> + + <row> + <entry role="func_table_entry"><para role="func_signature"> + <indexterm> + <primary>next</primary> + </indexterm> + <function>next</function> ( <parameter>value</parameter> <type>anyelement</type> ) + <returnvalue>anyelement</returnvalue> + </para> + <para> + Returns the column value at the next row; + returns NULL if there is no next row in the window frame. + </para></entry> + </row> + + </tbody> + </tgroup> + </table> + <note> <para> The SQL standard defines a <literal>RESPECT NULLS</literal> or diff --git a/doc/src/sgml/ref/select.sgml b/doc/src/sgml/ref/select.sgml index 066aed44e6..8f18718d58 100644 --- a/doc/src/sgml/ref/select.sgml +++ b/doc/src/sgml/ref/select.sgml @@ -969,8 +969,8 @@ WINDOW <replaceable class="parameter">window_name</replaceable> AS ( <replaceabl The <replaceable class="parameter">frame_clause</replaceable> can be one of <synopsis> -{ RANGE | ROWS | GROUPS } <replaceable>frame_start</replaceable> [ <replaceable>frame_exclusion</replaceable> ] -{ RANGE | ROWS | GROUPS } BETWEEN <replaceable>frame_start</replaceable> AND <replaceable>frame_end</replaceable> [ <replaceable>frame_exclusion</replaceable> ] +{ RANGE | ROWS | GROUPS } <replaceable>frame_start</replaceable> [ <replaceable>frame_exclusion</replaceable> ] [row_pattern_common_syntax] +{ RANGE | ROWS | GROUPS } BETWEEN <replaceable>frame_start</replaceable> AND <replaceable>frame_end</replaceable> [ <replaceable>frame_exclusion</replaceable> ] [row_pattern_common_syntax] </synopsis> where <replaceable>frame_start</replaceable> @@ -1077,6 +1077,40 @@ EXCLUDE NO OTHERS a given peer group will be in the frame or excluded from it. </para> + <para> + The + optional <replaceable class="parameter">row_pattern_common_syntax</replaceable> + defines the <firstterm>row pattern recognition condition</firstterm> for + this + window. <replaceable class="parameter">row_pattern_common_syntax</replaceable> + includes following subclauses. <literal>AFTER MATCH SKIP PAST LAST + ROW</literal> or <literal>AFTER MATCH SKIP TO NEXT ROW</literal> controls + how to proceed to next row position after a match + found. With <literal>AFTER MATCH SKIP PAST LAST ROW</literal> (the + default) next row position is next to the last row of previous match. On + the other hand, with <literal>AFTER MATCH SKIP TO NEXT ROW</literal> next + row position is always next to the last row of previous + match. <literal>DEFINE</literal> defines definition variables along with a + boolean expression. <literal>PATTERN</literal> defines a sequence of rows + that satisfies certain conditions using variables defined + in <literal>DEFINE</literal> clause. If the variable is not defined in + the <literal>DEFINE</literal> clause, it is implicitly assumed + following is defined in the <literal>DEFINE</literal> clause. + +<synopsis> +<literal>variable_name</literal> AS TRUE +</synopsis> + + Note that the maximu number of variables defined + in <literal>DEFINE</literal> clause is 26. + +<synopsis> +[ AFTER MATCH SKIP PAST LAST ROW | AFTER MATCH SKIP TO NEXT ROW ] +PATTERN <replaceable class="parameter">pattern_variable_name</replaceable>[+] [, ...] +DEFINE <replaceable class="parameter">definition_varible_name</replaceable> AS <replaceable class="parameter">expression</replaceable> [, ...] +</synopsis> + </para> + <para> The purpose of a <literal>WINDOW</literal> clause is to specify the behavior of <firstterm>window functions</firstterm> appearing in the query's -- 2.25.1 ----Next_Part(Thu_Mar_28_19_59_25_2024_076)-- Content-Type: Text/X-Patch; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="v15-0007-Row-pattern-recognition-patch-tests.patch" ^ permalink raw reply [nested|flat] 2+ messages in thread
end of thread, other threads:[~2024-03-28 10:30 UTC | newest] Thread overview: 2+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2021-01-18 05:47 [PATCH v4] Do not use RelationNeedsWAL to identify relation persistence Kyotaro Horiguchi <[email protected]> 2024-03-28 10:30 [PATCH v15 6/8] Row pattern recognition patch (docs). Tatsuo Ishii <[email protected]>
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