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Re: subscription/015_stream sometimes breaks 4+ messages / 3 participants [nested] [flat]
* Re: subscription/015_stream sometimes breaks @ 2023-08-25 10:15 Amit Kapila <[email protected]> 0 siblings, 1 reply; 4+ messages in thread From: Amit Kapila @ 2023-08-25 10:15 UTC (permalink / raw) To: Alvaro Herrera <[email protected]>; +Cc: Zhijie Hou (Fujitsu) <[email protected]>; Thomas Munro <[email protected]>; pgsql-hackers On Thu, Aug 24, 2023 at 3:48 PM Amit Kapila <[email protected]> wrote: > > On Thu, Aug 24, 2023 at 1:20 PM Alvaro Herrera <[email protected]> wrote: > > > > On 2023-Aug-24, Amit Kapila wrote: > > > > > On Wed, Aug 23, 2023 at 1:31 PM Alvaro Herrera <[email protected]> wrote: > > > > > > Hmm, I think if worker->in_use is false, we shouldn't consult the rest > > > > of the struct at all, so I propose to add the attached 0001 as a minimal > > > > fix. > > > > > > I think that way we may need to add the check for in_use before > > > accessing each of the LogicalRepWorker struct fields or form some rule > > > about which fields (or places) are okay to access without checking > > > in_use field. > > > > As far as I realize, we have that rule already. It's only a few > > relatively new places that have broken it. I understand that the in_use > > concept comes from the one of the same name in ReplicationSlot, except > > that it is not at all documented in worker_internal.h. > > > > So I propose we do both: apply Zhijie's patch and my 0001 now; and > > somebody gets to document the locking design for LogicalRepWorker. > > > > Agreed. > Pushed both the patches. -- With Regards, Amit Kapila. ^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: subscription/015_stream sometimes breaks @ 2023-08-28 00:04 Peter Smith <[email protected]> parent: Amit Kapila <[email protected]> 0 siblings, 1 reply; 4+ messages in thread From: Peter Smith @ 2023-08-28 00:04 UTC (permalink / raw) To: Amit Kapila <[email protected]>; +Cc: Alvaro Herrera <[email protected]>; Zhijie Hou (Fujitsu) <[email protected]>; Thomas Munro <[email protected]>; pgsql-hackers On Fri, Aug 25, 2023 at 8:15 PM Amit Kapila <[email protected]> wrote: > > On Thu, Aug 24, 2023 at 3:48 PM Amit Kapila <[email protected]> wrote: > > > > On Thu, Aug 24, 2023 at 1:20 PM Alvaro Herrera <[email protected]> wrote: > > > > > > On 2023-Aug-24, Amit Kapila wrote: > > > > > > > On Wed, Aug 23, 2023 at 1:31 PM Alvaro Herrera <[email protected]> wrote: > > > > > > > > Hmm, I think if worker->in_use is false, we shouldn't consult the rest > > > > > of the struct at all, so I propose to add the attached 0001 as a minimal > > > > > fix. > > > > > > > > I think that way we may need to add the check for in_use before > > > > accessing each of the LogicalRepWorker struct fields or form some rule > > > > about which fields (or places) are okay to access without checking > > > > in_use field. > > > > > > As far as I realize, we have that rule already. It's only a few > > > relatively new places that have broken it. I understand that the in_use > > > concept comes from the one of the same name in ReplicationSlot, except > > > that it is not at all documented in worker_internal.h. > > > > > > So I propose we do both: apply Zhijie's patch and my 0001 now; and > > > somebody gets to document the locking design for LogicalRepWorker. > > > > > > > Agreed. > > > > Pushed both the patches. > IMO there are inconsistencies in the second patch that was pushed. 1. In the am_xxx functions, why is there Assert 'in_use' only for the APPLY / PARALLEL_APPLY workers but not for TABLESYNC workers? 2. In the am_xxx functions there is now Assert 'in_use', so why are we still using macros to check again what we already asserted is not possible? (Or, if the checking overkill was a deliberate choice then why is there no isLeaderApplyWorker macro?) ~ PSA a small patch to address these. ------ Kind Regards, Peter Smith. Fujitsu Australia Attachments: [application/octet-stream] v1-0001-Fix-am_xxx-function-Asserts.patch (1.1K, ../../CAHut+PuwaF4Sb41pWQk69d2WO_ZJQpj-_2JkQvP=1jwozUpcCQ@mail.gmail.com/2-v1-0001-Fix-am_xxx-function-Asserts.patch) download | inline diff: From abe9f4c56d931e12f6e8a9e3d1c1d88fff7e4149 Mon Sep 17 00:00:00 2001 From: Peter Smith <[email protected]> Date: Mon, 28 Aug 2023 09:29:50 +1000 Subject: [PATCH v1] Fix am_xxx function Asserts --- src/include/replication/worker_internal.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/src/include/replication/worker_internal.h b/src/include/replication/worker_internal.h index 8f4bed0..dd94543 100644 --- a/src/include/replication/worker_internal.h +++ b/src/include/replication/worker_internal.h @@ -335,7 +335,8 @@ extern void pa_xact_finish(ParallelApplyWorkerInfo *winfo, static inline bool am_tablesync_worker(void) { - return isTablesyncWorker(MyLogicalRepWorker); + Assert(MyLogicalRepWorker->in_use); + return (MyLogicalRepWorker->type == WORKERTYPE_TABLESYNC); } static inline bool @@ -349,7 +350,7 @@ static inline bool am_parallel_apply_worker(void) { Assert(MyLogicalRepWorker->in_use); - return isParallelApplyWorker(MyLogicalRepWorker); + return (MyLogicalRepWorker->type == WORKERTYPE_PARALLEL_APPLY); } #endif /* WORKER_INTERNAL_H */ -- 1.8.3.1 ^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: subscription/015_stream sometimes breaks @ 2023-08-29 04:18 Amit Kapila <[email protected]> parent: Peter Smith <[email protected]> 0 siblings, 0 replies; 4+ messages in thread From: Amit Kapila @ 2023-08-29 04:18 UTC (permalink / raw) To: Peter Smith <[email protected]>; +Cc: Alvaro Herrera <[email protected]>; Zhijie Hou (Fujitsu) <[email protected]>; Thomas Munro <[email protected]>; pgsql-hackers On Mon, Aug 28, 2023 at 5:35 AM Peter Smith <[email protected]> wrote: > > On Fri, Aug 25, 2023 at 8:15 PM Amit Kapila <[email protected]> wrote: > > IMO there are inconsistencies in the second patch that was pushed. > > 1. In the am_xxx functions, why is there Assert 'in_use' only for the > APPLY / PARALLEL_APPLY workers but not for TABLESYNC workers? > > 2. In the am_xxx functions there is now Assert 'in_use', so why are we > still using macros to check again what we already asserted is not > possible? (Or, if the checking overkill was a deliberate choice then > why is there no isLeaderApplyWorker macro?) > > ~ > > PSA a small patch to address these. > I find your suggestions reasonable. Alvaro, do you have any comments? -- With Regards, Amit Kapila. ^ permalink raw reply [nested|flat] 4+ messages in thread
* [PATCH v6 5/7] Row pattern recognition patch (docs). @ 2023-09-12 05:22 Tatsuo Ishii <[email protected]> 0 siblings, 0 replies; 4+ messages in thread From: Tatsuo Ishii @ 2023-09-12 05:22 UTC (permalink / raw) --- doc/src/sgml/advanced.sgml | 52 ++++++++++++++++++++++++++++++++++ doc/src/sgml/func.sgml | 54 ++++++++++++++++++++++++++++++++++++ doc/src/sgml/ref/select.sgml | 38 +++++++++++++++++++++++-- 3 files changed, 142 insertions(+), 2 deletions(-) diff --git a/doc/src/sgml/advanced.sgml b/doc/src/sgml/advanced.sgml index 755c9f1485..eda3612822 100644 --- a/doc/src/sgml/advanced.sgml +++ b/doc/src/sgml/advanced.sgml @@ -537,6 +537,58 @@ WHERE pos < 3; <literal>rank</literal> less than 3. </para> + <para> + Row pattern common syntax can be used with row pattern common syntax to + perform row pattern recognition in a query. Row pattern common syntax + includes two sub clauses. <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>. Moreover if the expression comprises a column + reference, it must be the argument of <function>rpr</function>. 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 price column in the previous + row if it's called in a context of row pattern recognition. So in the + second line means the definition variable "UP" is <literal>TRUE</literal> + when price column in the current row is greater than the price column in + the previous row. Likewise, "DOWN" is <literal>TRUE</literal> when when + 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". If a + sequence of rows found, rpr returns the column at the starting row. + Example of a <literal>SELECT</literal> using the <literal>DEFINE</literal> + and <literal>PATTERN</literal> clause is as follows. + +<programlisting> +SELECT company, tdate, price, max(price) OVER w FROM stock + WINDOW w AS ( + PARTITION BY company + 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> + </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 24ad87f910..9c99dda4ae 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -21780,6 +21780,7 @@ SELECT count(*) FROM sometable; returns <literal>NULL</literal> if there is no such row. </para></entry> </row> + </tbody> </tgroup> </table> @@ -21819,6 +21820,59 @@ 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 0ee0cc7e64..8d3becd57a 100644 --- a/doc/src/sgml/ref/select.sgml +++ b/doc/src/sgml/ref/select.sgml @@ -966,8 +966,8 @@ 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> @@ -1074,6 +1074,40 @@ 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(Tue_Sep_12_15_18_43_2023_359)-- Content-Type: Text/X-Patch; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="v6-0006-Row-pattern-recognition-patch-tests.patch" ^ permalink raw reply [nested|flat] 4+ messages in thread
end of thread, other threads:[~2023-09-12 05:22 UTC | newest] Thread overview: 4+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2023-08-25 10:15 Re: subscription/015_stream sometimes breaks Amit Kapila <[email protected]> 2023-08-28 00:04 ` Peter Smith <[email protected]> 2023-08-29 04:18 ` Amit Kapila <[email protected]> 2023-09-12 05:22 [PATCH v6 5/7] Row pattern recognition patch (docs). Tatsuo Ishii <[email protected]>
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