mirror of https://github.com/postgres/postgres
Make postgres_fdw's "Relations" output agree with the rest of EXPLAIN.
The relation aliases shown in the "Relations" line for a foreign scan didn't always agree with those used in the rest of EXPLAIN's output. The regression test result changes appearing here provide examples. It's really impossible for postgres_fdw to duplicate EXPLAIN's alias assignment logic during postgresGetForeignRelSize(), because of the de-duplication that EXPLAIN does on a global basis --- and anyway, trying to duplicate that would be unmaintainable. Instead, just put numeric rangetable indexes into the string, and convert those to table names/aliases in postgresExplainForeignScan, which does have access to the results of ruleutils.c's alias assignment logic. Aside from being more reliable, this shifts some work from planning to EXPLAIN, which is a good tradeoff for performance. (I also changed from using StringInfo to using psprintf, which makes the code slightly simpler and reduces its memory consumption.) A kluge required by this solution is that we have to reverse-engineer the rtoffset applied by setrefs.c. If that logic ever fails (presumably because the member tables of a join got offset by different amounts), we'll need some more cooperation with setrefs.c to keep things straight. But for now, there's no need for that. Arguably this is a back-patchable bug fix, but since this is a mostly cosmetic issue and there have been no field complaints, I'll refrain for now. Discussion: https://postgr.es/m/12424.1575168015@sss.pgh.pa.us
This commit is contained in:
Tom Lane
parent
1d468b9ad8
commit
4526951d56
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@ -1348,7 +1348,7 @@ SELECT t1.c1, ss.a, ss.b FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t1
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--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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Foreign Scan
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Output: ft4.c1, ft4_1.c1, ft5.c1
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Relations: (public.ft4) FULL JOIN ((public.ft4) FULL JOIN (public.ft5))
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Relations: (public.ft4) FULL JOIN ((public.ft4 ft4_1) FULL JOIN (public.ft5))
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Remote SQL: SELECT s4.c1, s10.c1, s10.c2 FROM ((SELECT c1 FROM "S 1"."T 3" WHERE ((c1 >= 50)) AND ((c1 <= 60))) s4(c1) FULL JOIN (SELECT s8.c1, s9.c1 FROM ((SELECT c1 FROM "S 1"."T 3" WHERE ((c1 >= 50)) AND ((c1 <= 60))) s8(c1) FULL JOIN (SELECT c1 FROM "S 1"."T 4" WHERE ((c1 >= 50)) AND ((c1 <= 60))) s9(c1) ON (((s8.c1 = s9.c1)))) WHERE (((s8.c1 IS NULL) OR (s8.c1 IS NOT NULL)))) s10(c1, c2) ON (((s4.c1 = s10.c1)))) ORDER BY s4.c1 ASC NULLS LAST, s10.c1 ASC NULLS LAST, s10.c2 ASC NULLS LAST
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(4 rows)
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@ -2084,7 +2084,7 @@ SELECT t1c1, avg(t1c1 + t2c1) FROM (SELECT t1.c1, t2.c1 FROM ft1 t1 JOIN ft2 t2
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Remote SQL: SELECT r1."C 1", r2."C 1" FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (((r1."C 1" = r2."C 1"))))
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-> Foreign Scan
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Output: t1_1.c1, t2_1.c1
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Relations: (public.ft1 t1) INNER JOIN (public.ft2 t2)
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Relations: (public.ft1 t1_1) INNER JOIN (public.ft2 t2_1)
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Remote SQL: SELECT r1."C 1", r2."C 1" FROM ("S 1"."T 1" r1 INNER JOIN "S 1"."T 1" r2 ON (((r1."C 1" = r2."C 1"))))
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(20 rows)
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@ -3230,7 +3230,7 @@ select count(*), x.b from ft1, (select c2 a, sum(c1) b from ft1 group by c2) x w
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Output: x.b, x.a
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-> Foreign Scan
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Output: ft1_1.c2, (sum(ft1_1.c1))
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Relations: Aggregate on (public.ft1)
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Relations: Aggregate on (public.ft1 ft1_1)
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Remote SQL: SELECT c2, sum("C 1") FROM "S 1"."T 1" GROUP BY 1
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(21 rows)
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@ -8481,14 +8481,14 @@ ANALYZE fprt2_p2;
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EXPLAIN (COSTS OFF)
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SELECT t1.a,t2.b,t3.c FROM fprt1 t1 INNER JOIN fprt2 t2 ON (t1.a = t2.b) INNER JOIN fprt1 t3 ON (t2.b = t3.a) WHERE t1.a % 25 =0 ORDER BY 1,2,3;
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QUERY PLAN
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--------------------------------------------------------------------------------------------------------------------
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--------------------------------------------------------------------------------------------------------------------------
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Sort
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Sort Key: t1.a, t3.c
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-> Append
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-> Foreign Scan
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Relations: ((public.ftprt1_p1 t1) INNER JOIN (public.ftprt2_p1 t2)) INNER JOIN (public.ftprt1_p1 t3)
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-> Foreign Scan
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Relations: ((public.ftprt1_p2 t1) INNER JOIN (public.ftprt2_p2 t2)) INNER JOIN (public.ftprt1_p2 t3)
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Relations: ((public.ftprt1_p2 t1_1) INNER JOIN (public.ftprt2_p2 t2_1)) INNER JOIN (public.ftprt1_p2 t3_1)
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(7 rows)
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SELECT t1.a,t2.b,t3.c FROM fprt1 t1 INNER JOIN fprt2 t2 ON (t1.a = t2.b) INNER JOIN fprt1 t3 ON (t2.b = t3.a) WHERE t1.a % 25 =0 ORDER BY 1,2,3;
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@ -8507,7 +8507,7 @@ SELECT t1.a,t2.b,t2.c FROM fprt1 t1 LEFT JOIN (SELECT * FROM fprt2 WHERE a < 10)
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----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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Foreign Scan
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Output: t1.a, ftprt2_p1.b, ftprt2_p1.c
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Relations: (public.ftprt1_p1 t1) LEFT JOIN (public.ftprt2_p1 fprt2)
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Relations: (public.ftprt1_p1 t1) LEFT JOIN (public.ftprt2_p1)
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Remote SQL: SELECT r5.a, r6.b, r6.c FROM (public.fprt1_p1 r5 LEFT JOIN public.fprt2_p1 r6 ON (((r5.a = r6.b)) AND ((r5.b = r6.a)) AND ((r6.a < 10)))) WHERE ((r5.a < 10)) ORDER BY r5.a ASC NULLS LAST, r6.b ASC NULLS LAST, r6.c ASC NULLS LAST
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(4 rows)
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@ -8562,14 +8562,14 @@ SELECT t1.wr, t2.wr FROM (SELECT t1 wr, a FROM fprt1 t1 WHERE t1.a % 25 = 0) t1
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EXPLAIN (COSTS OFF)
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SELECT t1.a,t1.b FROM fprt1 t1, LATERAL (SELECT t2.a, t2.b FROM fprt2 t2 WHERE t1.a = t2.b AND t1.b = t2.a) q WHERE t1.a%25 = 0 ORDER BY 1,2;
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QUERY PLAN
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---------------------------------------------------------------------------------
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-------------------------------------------------------------------------------------
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Sort
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Sort Key: t1.a, t1.b
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-> Append
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-> Foreign Scan
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Relations: (public.ftprt1_p1 t1) INNER JOIN (public.ftprt2_p1 t2)
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-> Foreign Scan
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Relations: (public.ftprt1_p2 t1) INNER JOIN (public.ftprt2_p2 t2)
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Relations: (public.ftprt1_p2 t1_1) INNER JOIN (public.ftprt2_p2 t2_1)
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(7 rows)
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SELECT t1.a,t1.b FROM fprt1 t1, LATERAL (SELECT t2.a, t2.b FROM fprt2 t2 WHERE t1.a = t2.b AND t1.b = t2.a) q WHERE t1.a%25 = 0 ORDER BY 1,2;
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@ -8690,16 +8690,16 @@ SET enable_partitionwise_aggregate TO true;
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EXPLAIN (COSTS OFF)
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SELECT a, sum(b), min(b), count(*) FROM pagg_tab GROUP BY a HAVING avg(b) < 22 ORDER BY 1;
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QUERY PLAN
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----------------------------------------------------------------------
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-------------------------------------------------------------
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Sort
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Sort Key: fpagg_tab_p1.a
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-> Append
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-> Foreign Scan
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Relations: Aggregate on (public.fpagg_tab_p1 pagg_tab)
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Relations: Aggregate on (public.fpagg_tab_p1)
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-> Foreign Scan
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Relations: Aggregate on (public.fpagg_tab_p2 pagg_tab)
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Relations: Aggregate on (public.fpagg_tab_p2)
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-> Foreign Scan
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Relations: Aggregate on (public.fpagg_tab_p3 pagg_tab)
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Relations: Aggregate on (public.fpagg_tab_p3)
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(9 rows)
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SELECT a, sum(b), min(b), count(*) FROM pagg_tab GROUP BY a HAVING avg(b) < 22 ORDER BY 1;
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@ -12,6 +12,8 @@
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*/
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#include "postgres.h"
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#include <limits.h>
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#include "access/htup_details.h"
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#include "access/sysattr.h"
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#include "access/table.h"
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@ -574,9 +576,6 @@ postgresGetForeignRelSize(PlannerInfo *root,
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PgFdwRelationInfo *fpinfo;
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ListCell *lc;
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RangeTblEntry *rte = planner_rt_fetch(baserel->relid, root);
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const char *namespace;
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const char *relname;
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const char *refname;
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/*
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* We use PgFdwRelationInfo to pass various information to subsequent
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@ -719,21 +718,11 @@ postgresGetForeignRelSize(PlannerInfo *root,
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}
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/*
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* Set the name of relation in fpinfo, while we are constructing it here.
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* It will be used to build the string describing the join relation in
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* EXPLAIN output. We can't know whether VERBOSE option is specified or
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* not, so always schema-qualify the foreign table name.
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* fpinfo->relation_name gets the numeric rangetable index of the foreign
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* table RTE. (If this query gets EXPLAIN'd, we'll convert that to a
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* human-readable string at that time.)
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*/
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fpinfo->relation_name = makeStringInfo();
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namespace = get_namespace_name(get_rel_namespace(foreigntableid));
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relname = get_rel_name(foreigntableid);
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refname = rte->eref->aliasname;
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appendStringInfo(fpinfo->relation_name, "%s.%s",
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quote_identifier(namespace),
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quote_identifier(relname));
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if (*refname && strcmp(refname, relname) != 0)
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appendStringInfo(fpinfo->relation_name, " %s",
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quote_identifier(rte->eref->aliasname));
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fpinfo->relation_name = psprintf("%u", baserel->relid);
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/* No outer and inner relations. */
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fpinfo->make_outerrel_subquery = false;
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@ -1376,7 +1365,7 @@ postgresGetForeignPlan(PlannerInfo *root,
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makeInteger(fpinfo->fetch_size));
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if (IS_JOIN_REL(foreignrel) || IS_UPPER_REL(foreignrel))
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fdw_private = lappend(fdw_private,
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makeString(fpinfo->relation_name->data));
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makeString(fpinfo->relation_name));
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/*
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* Create the ForeignScan node for the given relation.
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@ -2528,20 +2517,85 @@ postgresEndDirectModify(ForeignScanState *node)
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static void
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postgresExplainForeignScan(ForeignScanState *node, ExplainState *es)
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{
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List *fdw_private;
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char *sql;
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char *relations;
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fdw_private = ((ForeignScan *) node->ss.ps.plan)->fdw_private;
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ForeignScan *plan = castNode(ForeignScan, node->ss.ps.plan);
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List *fdw_private = plan->fdw_private;
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/*
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* Add names of relation handled by the foreign scan when the scan is a
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* join
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* Identify foreign scans that are really joins or upper relations. The
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* input looks something like "(1) LEFT JOIN (2)", and we must replace the
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* digit string(s), which are RT indexes, with the correct relation names.
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* We do that here, not when the plan is created, because we can't know
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* what aliases ruleutils.c will assign at plan creation time.
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*/
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if (list_length(fdw_private) > FdwScanPrivateRelations)
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{
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relations = strVal(list_nth(fdw_private, FdwScanPrivateRelations));
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ExplainPropertyText("Relations", relations, es);
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StringInfo relations;
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char *rawrelations;
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char *ptr;
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int minrti,
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rtoffset;
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rawrelations = strVal(list_nth(fdw_private, FdwScanPrivateRelations));
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/*
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* A difficulty with using a string representation of RT indexes is
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* that setrefs.c won't update the string when flattening the
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* rangetable. To find out what rtoffset was applied, identify the
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* minimum RT index appearing in the string and compare it to the
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* minimum member of plan->fs_relids. (We expect all the relids in
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* the join will have been offset by the same amount; the Asserts
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* below should catch it if that ever changes.)
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*/
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minrti = INT_MAX;
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ptr = rawrelations;
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while (*ptr)
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{
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if (isdigit((unsigned char) *ptr))
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{
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int rti = strtol(ptr, &ptr, 10);
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if (rti < minrti)
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minrti = rti;
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}
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else
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ptr++;
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}
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rtoffset = bms_next_member(plan->fs_relids, -1) - minrti;
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/* Now we can translate the string */
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relations = makeStringInfo();
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ptr = rawrelations;
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while (*ptr)
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{
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if (isdigit((unsigned char) *ptr))
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{
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int rti = strtol(ptr, &ptr, 10);
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RangeTblEntry *rte;
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char *namespace;
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char *relname;
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char *refname;
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rti += rtoffset;
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Assert(bms_is_member(rti, plan->fs_relids));
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rte = rt_fetch(rti, es->rtable);
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Assert(rte->rtekind == RTE_RELATION);
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/* This logic should agree with explain.c's ExplainTargetRel */
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namespace = get_namespace_name(get_rel_namespace(rte->relid));
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relname = get_rel_name(rte->relid);
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appendStringInfo(relations, "%s.%s",
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quote_identifier(namespace),
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quote_identifier(relname));
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refname = (char *) list_nth(es->rtable_names, rti - 1);
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if (refname == NULL)
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refname = rte->eref->aliasname;
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if (strcmp(refname, relname) != 0)
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appendStringInfo(relations, " %s",
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quote_identifier(refname));
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}
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else
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appendStringInfoChar(relations, *ptr++);
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}
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ExplainPropertyText("Relations", relations->data, es);
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}
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/*
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@ -2549,6 +2603,8 @@ postgresExplainForeignScan(ForeignScanState *node, ExplainState *es)
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*/
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if (es->verbose)
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{
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char *sql;
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sql = strVal(list_nth(fdw_private, FdwScanPrivateSelectSql));
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ExplainPropertyText("Remote SQL", sql, es);
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}
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@ -5171,13 +5227,14 @@ foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
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/*
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* Set the string describing this join relation to be used in EXPLAIN
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* output of corresponding ForeignScan.
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* output of corresponding ForeignScan. Note that the decoration we add
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* to the base relation names mustn't include any digits, or it'll confuse
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* postgresExplainForeignScan.
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*/
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fpinfo->relation_name = makeStringInfo();
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appendStringInfo(fpinfo->relation_name, "(%s) %s JOIN (%s)",
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fpinfo_o->relation_name->data,
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fpinfo->relation_name = psprintf("(%s) %s JOIN (%s)",
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fpinfo_o->relation_name,
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get_jointype_name(fpinfo->jointype),
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fpinfo_i->relation_name->data);
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fpinfo_i->relation_name);
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/*
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* Set the relation index. This is defined as the position of this
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@ -5723,11 +5780,12 @@ foreign_grouping_ok(PlannerInfo *root, RelOptInfo *grouped_rel,
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/*
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* Set the string describing this grouped relation to be used in EXPLAIN
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* output of corresponding ForeignScan.
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* output of corresponding ForeignScan. Note that the decoration we add
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* to the base relation name mustn't include any digits, or it'll confuse
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* postgresExplainForeignScan.
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*/
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fpinfo->relation_name = makeStringInfo();
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appendStringInfo(fpinfo->relation_name, "Aggregate on (%s)",
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ofpinfo->relation_name->data);
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fpinfo->relation_name = psprintf("Aggregate on (%s)",
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ofpinfo->relation_name);
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return true;
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}
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@ -87,11 +87,14 @@ typedef struct PgFdwRelationInfo
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int fetch_size; /* fetch size for this remote table */
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/*
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* Name of the relation while EXPLAINing ForeignScan. It is used for join
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* relations but is set for all relations. For join relation, the name
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* indicates which foreign tables are being joined and the join type used.
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* Name of the relation, for use while EXPLAINing ForeignScan. It is used
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* for join and upper relations but is set for all relations. For a base
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* relation, this is really just the RT index as a string; we convert that
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* while producing EXPLAIN output. For join and upper relations, the name
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* indicates which base foreign tables are included and the join type or
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* aggregation type used.
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*/
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StringInfo relation_name;
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char *relation_name;
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/* Join information */
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RelOptInfo *outerrel;
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