Re: [PATCH] Provide rowcount for utility SELECTs

Applied. Thanks.

---------------------------------------------------------------------------

Bruce Momjian wrote:
> Boszormenyi Zoltan wrote:
> > >>> Ah, I didn't even see that that section needed to be updated. Good
> > >>> catch. I'd suggest the following wording:
> > >>>
> > >>> For a <command>SELECT</command> or <command>CREATE TABLE AS</command>
> > >>> command, the tag is SELECT rows... [and the rest as you have it]
> > >>>
> > >>> We should probably also retitle that section from "Retrieving Result
> > >>> Information for Other Commands" to "Retrieving Other Result
> > >>> Information" and adjust the text of the opening sentence similarly.
> > >>>
> > >>> Also I think you need to update the docs for PQcmdtuples to mention
> > >>> that it not works for SELECT and CTAS.
> > >>>
> > >>>
> > >> Ok, I will update libpq.sgml where this section resides.
> > >> What's a CTA, btw? Do you mean CTE, a.k.a. "Common Table Expression"?
> > >>
> > >
> > > Sorry, CTAS = CREATE TABLE AS SELECT.
> > >
> >
> > Okay, new patch is attached. Please read the docs changes, and comment.
>
> I have reviewed this patch and made some adjustments, attached. The
> major change is that our return of "0 0" in certain cases must remain,
> though I have improved the C comment explaining it with a separate CVS
> commit:
>
> /*
> * If a command completion tag was supplied, use it. Otherwise use the
> * portal's commandTag as the default completion tag.
> *
> * Exception: Clients expect INSERT/UPDATE/DELETE tags to have
> * counts, so fake them with zeros. This can happen with DO INSTEAD
> * rules if there is no replacement query of the same type as the
> * original. We print "0 0" here because technically there is no
> * query of the matching tag type, and printing a non-zero count for
> * a different query type seems wrong, e.g. an INSERT that does
> * an UPDATE instead should not print "0 1" if one row
> * was updated. See QueryRewrite(), step 3, for details.
> */
>
> I have removed the part of the patch that chagned "0 0"; it seems to
> run fine without it. The rest of my adjustments were minor.
>
> One major part of the patch seems to be the collection of the
> PORTAL_ONE_SELECT switch label into the label below it, which is a nice
> cleanup.
>
> --
> Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
> EnterpriseDB http://enterprisedb.com
>
> + If your life is a hard drive, Christ can be your backup. +

> Index: doc/src/sgml/libpq.sgml
> ===================================================================
> RCS file: /cvsroot/pgsql/doc/src/sgml/libpq.sgml,v
> retrieving revision 1.297
> diff -c -c -r1.297 libpq.sgml
> *** doc/src/sgml/libpq.sgml 5 Feb 2010 03:09:04 -0000 1.297
> --- doc/src/sgml/libpq.sgml 14 Feb 2010 03:11:00 -0000
> ***************
> *** 2869,2880 ****
> </sect2>
>
> <sect2 id="libpq-exec-nonselect">
> ! <title>Retrieving Result Information for Other Commands</title>
>
> <para>
> ! These functions are used to extract information from
> ! <structname>PGresult</structname> objects that are not
> ! <command>SELECT</> results.
> </para>
>
> <variablelist>
> --- 2869,2879 ----
> </sect2>
>
> <sect2 id="libpq-exec-nonselect">
> ! <title>Retrieving Other Result Information</title>
>
> <para>
> ! These functions are used to extract other information from
> ! <structname>PGresult</structname> objects.
> </para>
>
> <variablelist>
> ***************
> *** 2925,2936 ****
> This function returns a string containing the number of rows
> affected by the <acronym>SQL</> statement that generated the
> <structname>PGresult</>. This function can only be used following
> ! the execution of an <command>INSERT</>, <command>UPDATE</>,
> ! <command>DELETE</>, <command>MOVE</>, <command>FETCH</>, or
> ! <command>COPY</> statement, or an <command>EXECUTE</> of a
> ! prepared query that contains an <command>INSERT</>,
> ! <command>UPDATE</>, or <command>DELETE</> statement. If the
> ! command that generated the <structname>PGresult</> was anything
> else, <function>PQcmdTuples</> returns an empty string. The caller
> should not free the return value directly. It will be freed when
> the associated <structname>PGresult</> handle is passed to
> --- 2924,2935 ----
> This function returns a string containing the number of rows
> affected by the <acronym>SQL</> statement that generated the
> <structname>PGresult</>. This function can only be used following
> ! the execution of a <command>SELECT</>, <command>CREATE TABLE AS</>,
> ! <command>INSERT</>, <command>UPDATE</>, <command>DELETE</>,
> ! <command>MOVE</>, <command>FETCH</>, or <command>COPY</> statement,
> ! or an <command>EXECUTE</> of a prepared query that contains an
> ! <command>INSERT</>, <command>UPDATE</>, or <command>DELETE</> statement.
> ! If the command that generated the <structname>PGresult</> was anything
> else, <function>PQcmdTuples</> returns an empty string. The caller
> should not free the return value directly. It will be freed when
> the associated <structname>PGresult</> handle is passed to
> Index: doc/src/sgml/protocol.sgml
> ===================================================================
> RCS file: /cvsroot/pgsql/doc/src/sgml/protocol.sgml,v
> retrieving revision 1.78
> diff -c -c -r1.78 protocol.sgml
> *** doc/src/sgml/protocol.sgml 3 Feb 2010 09:47:19 -0000 1.78
> --- doc/src/sgml/protocol.sgml 14 Feb 2010 03:11:00 -0000
> ***************
> *** 2222,2227 ****
> --- 2222,2233 ----
> </para>
>
> <para>
> + For a <command>SELECT</command> or <command>CREATE TABLE AS</command>
> + command, the tag is <literal>SELECT <replaceable>rows</replaceable></literal>
> + where <replaceable>rows</replaceable> is the number of rows retrieved.
> + </para>
> +
> + <para>
> For a <command>MOVE</command> command, the tag is
> <literal>MOVE <replaceable>rows</replaceable></literal> where
> <replaceable>rows</replaceable> is the number of rows the
> Index: src/backend/tcop/pquery.c
> ===================================================================
> RCS file: /cvsroot/pgsql/src/backend/tcop/pquery.c,v
> retrieving revision 1.135
> diff -c -c -r1.135 pquery.c
> *** src/backend/tcop/pquery.c 13 Feb 2010 22:45:41 -0000 1.135
> --- src/backend/tcop/pquery.c 14 Feb 2010 03:11:04 -0000
> ***************
> *** 205,211 ****
> switch (queryDesc->operation)
> {
> case CMD_SELECT:
> ! strcpy(completionTag, "SELECT");
> break;
> case CMD_INSERT:
> if (queryDesc->estate->es_processed == 1)
> --- 205,212 ----
> switch (queryDesc->operation)
> {
> case CMD_SELECT:
> ! snprintf(completionTag, COMPLETION_TAG_BUFSIZE,
> ! "SELECT %u", queryDesc->estate->es_processed);
> break;
> case CMD_INSERT:
> if (queryDesc->estate->es_processed == 1)
> ***************
> *** 714,719 ****
> --- 715,721 ----
> char *completionTag)
> {
> bool result;
> + uint32 nprocessed;
> ResourceOwner saveTopTransactionResourceOwner;
> MemoryContext saveTopTransactionContext;
> Portal saveActivePortal;
> ***************
> *** 776,814 ****
> switch (portal->strategy)
> {
> case PORTAL_ONE_SELECT:
> - (void) PortalRunSelect(portal, true, count, dest);
> -
> - /* we know the query is supposed to set the tag */
> - if (completionTag && portal->commandTag)
> - strcpy(completionTag, portal->commandTag);
> -
> - /* Mark portal not active */
> - portal->status = PORTAL_READY;
> -
> - /*
> - * Since it's a forward fetch, say DONE iff atEnd is now true.
> - */
> - result = portal->atEnd;
> - break;
> -
> case PORTAL_ONE_RETURNING:
> case PORTAL_UTIL_SELECT:
>
> /*
> * If we have not yet run the command, do so, storing its
> ! * results in the portal's tuplestore.
> */
> ! if (!portal->holdStore)
> FillPortalStore(portal, isTopLevel);
>
> /*
> * Now fetch desired portion of results.
> */
> ! (void) PortalRunSelect(portal, true, count, dest);
>
> ! /* we know the query is supposed to set the tag */
> if (completionTag && portal->commandTag)
> ! strcpy(completionTag, portal->commandTag);
>
> /* Mark portal not active */
> portal->status = PORTAL_READY;
> --- 778,812 ----
> switch (portal->strategy)
> {
> case PORTAL_ONE_SELECT:
> case PORTAL_ONE_RETURNING:
> case PORTAL_UTIL_SELECT:
>
> /*
> * If we have not yet run the command, do so, storing its
> ! * results in the portal's tuplestore. Do this only for the
> ! * PORTAL_ONE_RETURNING and PORTAL_UTIL_SELECT cases.
> */
> ! if (portal->strategy != PORTAL_ONE_SELECT && !portal->holdStore)
> FillPortalStore(portal, isTopLevel);
>
> /*
> * Now fetch desired portion of results.
> */
> ! nprocessed = PortalRunSelect(portal, true, count, dest);
>
> ! /*
> ! * If the portal result contains a command tag and the caller
> ! * gave us a pointer to store it, copy it. Patch the "SELECT"
> ! * tag to also provide the rowcount.
> ! */
> if (completionTag && portal->commandTag)
> ! {
> ! if (strcmp(portal->commandTag, "SELECT") == 0)
> ! snprintf(completionTag, COMPLETION_TAG_BUFSIZE,
> ! "SELECT %u", nprocessed);
> ! else
> ! strcpy(completionTag, portal->commandTag);
> ! }
>
> /* Mark portal not active */
> portal->status = PORTAL_READY;
> ***************
> *** 1331,1337 ****
> {
> if (portal->commandTag)
> strcpy(completionTag, portal->commandTag);
> ! if (strcmp(completionTag, "INSERT") == 0)
> strcpy(completionTag, "INSERT 0 0");
> else if (strcmp(completionTag, "UPDATE") == 0)
> strcpy(completionTag, "UPDATE 0");
> --- 1329,1337 ----
> {
> if (portal->commandTag)
> strcpy(completionTag, portal->commandTag);
> ! if (strcmp(completionTag, "SELECT") == 0)
> ! sprintf(completionTag, "SELECT 0 0");
> ! else if (strcmp(completionTag, "INSERT") == 0)
> strcpy(completionTag, "INSERT 0 0");
> else if (strcmp(completionTag, "UPDATE") == 0)
> strcpy(completionTag, "UPDATE 0");
> Index: src/interfaces/libpq/fe-exec.c
> ===================================================================
> RCS file: /cvsroot/pgsql/src/interfaces/libpq/fe-exec.c,v
> retrieving revision 1.208
> diff -c -c -r1.208 fe-exec.c
> *** src/interfaces/libpq/fe-exec.c 21 Jan 2010 18:43:25 -0000 1.208
> --- src/interfaces/libpq/fe-exec.c 14 Feb 2010 03:11:04 -0000
> ***************
> *** 2752,2758 ****
> goto interpret_error; /* no space? */
> p++;
> }
> ! else if (strncmp(res->cmdStatus, "DELETE ", 7) == 0 ||
> strncmp(res->cmdStatus, "UPDATE ", 7) == 0)
> p = res->cmdStatus + 7;
> else if (strncmp(res->cmdStatus, "FETCH ", 6) == 0)
> --- 2752,2759 ----
> goto interpret_error; /* no space? */
> p++;
> }
> ! else if (strncmp(res->cmdStatus, "SELECT ", 7) == 0 ||
> ! strncmp(res->cmdStatus, "DELETE ", 7) == 0 ||
> strncmp(res->cmdStatus, "UPDATE ", 7) == 0)
> p = res->cmdStatus + 7;
> else if (strncmp(res->cmdStatus, "FETCH ", 6) == 0)

>
> --
> Sent via pgsql-hackers mailing list (pgsql-hackers(at)postgresql(dot)org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-hackers

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

+ If your life is a hard drive, Christ can be your backup. +