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Commit0b69d8a

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committed
Rearrange top-level rewrite operations so that EXPLAIN works
on queries involving UNION, EXCEPT, INTERSECT.
1 parent6458daa commit0b69d8a

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3 files changed

+122
-103
lines changed

3 files changed

+122
-103
lines changed

‎src/backend/commands/explain.c‎

Lines changed: 11 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -4,7 +4,7 @@
44
*
55
* Copyright (c) 1994-5, Regents of the University of California
66
*
7-
* $Id: explain.c,v 1.35 1999/04/25 03:19:09 tgl Exp $
7+
* $Id: explain.c,v 1.36 1999/05/09 23:31:45 tgl Exp $
88
*
99
*/
1010
#include<stdio.h>
@@ -49,15 +49,18 @@ ExplainQuery(Query *query, bool verbose, CommandDest dest)
4949
List*rewritten;
5050
List*l;
5151

52+
/* rewriter and planner may not work in aborted state? */
5253
if (IsAbortedTransactionBlockState())
5354
{
54-
char*tag="*ABORT STATE*";
55-
56-
EndCommand(tag,dest);
57-
5855
elog(NOTICE,"(transaction aborted): %s",
5956
"queries ignored until END");
57+
return;
58+
}
6059

60+
/* rewriter and planner will not cope with utility statements */
61+
if (query->commandType==CMD_UTILITY)
62+
{
63+
elog(NOTICE,"Utility statements have no plan structure");
6164
return;
6265
}
6366

@@ -67,7 +70,7 @@ ExplainQuery(Query *query, bool verbose, CommandDest dest)
6770
/* In the case of an INSTEAD NOTHING, tell at least that */
6871
if (rewritten==NIL)
6972
{
70-
elog(NOTICE,"query rewrites to nothing");
73+
elog(NOTICE,"Query rewrites to nothing");
7174
return;
7275
}
7376

@@ -88,7 +91,7 @@ ExplainOneQuery(Query *query, bool verbose, CommandDest dest)
8891
Plan*plan;
8992
ExplainState*es;
9093

91-
/* plan thequeries (XXX we've ignored rewrite!!) */
94+
/* plan thequery */
9295
plan=planner(query);
9396

9497
/* pg_plan could have failed */
@@ -195,7 +198,7 @@ explain_outNode(StringInfo str, Plan *plan, int indent, ExplainState *es)
195198
pname="Hash";
196199
break;
197200
default:
198-
pname="";
201+
pname="???";
199202
break;
200203
}
201204

‎src/backend/rewrite/rewriteHandler.c‎

Lines changed: 54 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
*
77
*
88
* IDENTIFICATION
9-
* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteHandler.c,v 1.37 1999/02/22 05:26:46momjian Exp $
9+
* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteHandler.c,v 1.38 1999/05/09 23:31:46tgl Exp $
1010
*
1111
*-------------------------------------------------------------------------
1212
*/
@@ -59,8 +59,6 @@ static void modifyAggrefChangeVarnodes(Node **nodePtr, int rt_index, int new_ind
5959
staticvoidmodifyAggrefDropQual(Node**nodePtr,Node*orignode,Expr*expr);
6060
staticSubLink*modifyAggrefMakeSublink(Expr*origexp,Query*parsetree);
6161
staticvoidmodifyAggrefQual(Node**nodePtr,Query*parsetree);
62-
63-
6462
staticQuery*fireRIRrules(Query*parsetree);
6563

6664

@@ -2634,12 +2632,12 @@ RewritePreprocessQuery(Query *parsetree)
26342632

26352633

26362634
/*
2637-
*QueryRewrite -
2635+
*BasicQueryRewrite -
26382636
* rewrite one query via query rewrite system, possibly returning 0
26392637
* or many queries
26402638
*/
2641-
List*
2642-
QueryRewrite(Query*parsetree)
2639+
staticList*
2640+
BasicQueryRewrite(Query*parsetree)
26432641
{
26442642
List*querylist;
26452643
List*results=NIL;
@@ -2672,10 +2670,57 @@ QueryRewrite(Query *parsetree)
26722670
}
26732671
returnresults;
26742672
}
2675-
/***S*I***/
2676-
/* This function takes two targetlists as arguments and checks if the targetlists are compatible
2677-
* (i.e. both select for the same number of attributes and the types are compatible
2673+
2674+
/*
2675+
* QueryRewrite -
2676+
* Primary entry point to the query rewriter.
2677+
* Rewrite one query via query rewrite system, possibly returning 0
2678+
* or many queries.
2679+
*
2680+
* NOTE: The code in QueryRewrite was formerly in pg_parse_and_plan(), and was
2681+
* moved here so that it would be invoked during EXPLAIN. The division of
2682+
* labor between this routine and BasicQueryRewrite is not obviously correct
2683+
* ... at least not to me ... tgl 5/99.
26782684
*/
2685+
List*
2686+
QueryRewrite(Query*parsetree)
2687+
{
2688+
List*rewritten,
2689+
*rewritten_item;
2690+
2691+
/***S*I***/
2692+
/* Rewrite Union, Intersect and Except Queries
2693+
* to normal Union Queries using IN and NOT IN subselects */
2694+
if (parsetree->intersectClause)
2695+
parsetree=Except_Intersect_Rewrite(parsetree);
2696+
2697+
/* Rewrite basic queries (retrieve, append, delete, replace) */
2698+
rewritten=BasicQueryRewrite(parsetree);
2699+
2700+
/*
2701+
* Rewrite the UNIONS.
2702+
*/
2703+
foreach (rewritten_item,rewritten)
2704+
{
2705+
Query*qry= (Query*)lfirst(rewritten_item);
2706+
List*union_result=NIL;
2707+
List*union_item;
2708+
2709+
foreach (union_item,qry->unionClause)
2710+
{
2711+
union_result=nconc(union_result,
2712+
BasicQueryRewrite((Query*)lfirst(union_item)));
2713+
}
2714+
qry->unionClause=union_result;
2715+
}
2716+
2717+
returnrewritten;
2718+
}
2719+
2720+
/***S*I***/
2721+
/* This function takes two targetlists as arguments and checks if the
2722+
* targetlists are compatible (i.e. both select for the same number of
2723+
* attributes and the types are compatible */
26792724
voidcheck_targetlists_are_compatible(List*prev_target,List*current_target)
26802725
{
26812726
List*next_target;

‎src/backend/tcop/postgres.c‎

Lines changed: 57 additions & 86 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.110 1999/05/03 19:09:54 momjian Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.111 1999/05/09 23:31:47 tgl Exp $
1111
*
1212
* NOTES
1313
* this is the "main" module of the postgres backend and
@@ -399,6 +399,49 @@ pg_parse_and_plan(char *query_string,/* string to execute */
399399
List*rewritten=NIL;
400400
Query*querytree;
401401

402+
if (DebugPrintQuery)
403+
{
404+
if (DebugPrintQuery>3)
405+
{
406+
/* Print the query string as is if query debug level > 3 */
407+
TPRINTF(TRACE_QUERY,"query: %s",query_string);
408+
}
409+
else
410+
{
411+
/* Print condensed query string to fit in one log line */
412+
charbuff[MAX_QUERY_SIZE+1];
413+
charc,
414+
*s,
415+
*d;
416+
intn,
417+
is_space=1;
418+
419+
for (s=query_string,d=buff,n=0; (c=*s)&& (n<MAX_QUERY_SIZE);s++)
420+
{
421+
switch (c)
422+
{
423+
case'\r':
424+
case'\n':
425+
case'\t':
426+
c=' ';
427+
/* fall through */
428+
case' ':
429+
if (is_space)
430+
continue;
431+
is_space=1;
432+
break;
433+
default:
434+
is_space=0;
435+
break;
436+
}
437+
*d++=c;
438+
n++;
439+
}
440+
*d='\0';
441+
TPRINTF(TRACE_QUERY,"query: %s",buff);
442+
}
443+
}
444+
402445
/* ----------------
403446
*(1) parse the request string into a list of parse trees
404447
* ----------------
@@ -421,104 +464,37 @@ pg_parse_and_plan(char *query_string,/* string to execute */
421464

422465
/* ----------------
423466
*(2) rewrite the queries, as necessary
467+
*
468+
* j counts queries output into new_list; the number of rewritten
469+
* queries can be different from the original number.
424470
* ----------------
425471
*/
426-
j=0;/* counter for the new_list, new_list can
427-
* be longer than old list as a result of
428-
* rewrites */
472+
j=0;
429473
for (i=0;i<querytree_list->len;i++)
430474
{
431-
List*union_result,
432-
*union_list,
433-
*rewritten_list;
434-
435475
querytree=querytree_list->qtrees[i];
436476

437-
/***S*I***/
438-
/* Rewrite Union, Intersect and Except Queries
439-
* to normal Union Queries using IN and NOT IN subselects */
440-
if(querytree->intersectClause!=NIL)
441-
{
442-
querytree=Except_Intersect_Rewrite(querytree);
443-
}
444-
445-
if (DebugPrintQuery)
477+
if (DebugPrintParse)
446478
{
447-
if (DebugPrintQuery>3)
448-
{
449-
/* Print the query string as is if query debug level > 3 */
450-
TPRINTF(TRACE_QUERY,"query: %s",query_string);
451-
}
452-
else
453-
{
454-
/* Print condensed query string to fit in one log line */
455-
charbuff[MAX_QUERY_SIZE+1];
456-
charc,
457-
*s,
458-
*d;
459-
intn,
460-
is_space=1;
461-
462-
for (s=query_string,d=buff,n=0; (c=*s)&& (n<MAX_QUERY_SIZE);s++)
463-
{
464-
switch (c)
465-
{
466-
case'\r':
467-
case'\n':
468-
case'\t':
469-
c=' ';
470-
/* fall through */
471-
case' ':
472-
if (is_space)
473-
continue;
474-
is_space=1;
475-
break;
476-
default:
477-
is_space=0;
478-
break;
479-
}
480-
*d++=c;
481-
n++;
482-
}
483-
*d='\0';
484-
TPRINTF(TRACE_QUERY,"query: %s",buff);
485-
}
479+
TPRINTF(TRACE_PARSE,"parser outputs:");
480+
nodeDisplay(querytree);
486481
}
487482

488-
/* don't rewrite utilites */
483+
/* don't rewrite utilites, just dump 'em into new_list */
489484
if (querytree->commandType==CMD_UTILITY)
490485
{
491486
new_list->qtrees[j++]=querytree;
492487
continue;
493488
}
494489

495-
if (DebugPrintParse)
496-
{
497-
TPRINTF(TRACE_PARSE,"parser outputs:");
498-
nodeDisplay(querytree);
499-
}
500-
501-
/* rewrite queries (retrieve, append, delete, replace) */
490+
/* rewrite regular queries */
502491
rewritten=QueryRewrite(querytree);
503492

504493
if (rewritten!=NIL)
505494
{
506495
intlen,
507496
k;
508497

509-
/*
510-
* Rewrite the UNIONS.
511-
*/
512-
foreach(rewritten_list,rewritten)
513-
{
514-
Query*qry= (Query*)lfirst(rewritten_list);
515-
516-
union_result=NIL;
517-
foreach(union_list,qry->unionClause)
518-
union_result=nconc(union_result,QueryRewrite((Query*)lfirst(union_list)));
519-
qry->unionClause=union_result;
520-
}
521-
522498
len=length(rewritten);
523499
if (len==1)
524500
new_list->qtrees[j++]= (Query*)lfirst(rewritten);
@@ -530,19 +506,14 @@ pg_parse_and_plan(char *query_string,/* string to execute */
530506
* we allocated one space
531507
* for the query */
532508
new_list->qtrees=realloc(new_list->qtrees,
533-
new_list->len*sizeof(Query*));
509+
new_list->len*sizeof(Query*));
534510
for (k=0;k<len;k++)
535511
new_list->qtrees[j++]= (Query*)nth(k,rewritten);
536512
}
537513
}
538514
}
539515

540-
/* ----------
541-
* Due to rewriting, the new list could also have been
542-
* shrunk (do instead nothing). Forget obsolete queries
543-
* at the end.
544-
* ----------
545-
*/
516+
/* Update new_list with correct final length */
546517
new_list->len=j;
547518

548519
/* we're done with the original lists, free it */
@@ -657,7 +628,7 @@ pg_parse_and_plan(char *query_string,/* string to execute */
657628
}
658629

659630
/* ----------
660-
* Check if the rewriting had thrown awayanything
631+
* Check if the rewriting had thrown awayeverything
661632
* ----------
662633
*/
663634
if (querytree_list->len==0)
@@ -1539,7 +1510,7 @@ PostgresMain(int argc, char *argv[], int real_argc, char *real_argv[])
15391510
if (!IsUnderPostmaster)
15401511
{
15411512
puts("\nPOSTGRES backend interactive interface ");
1542-
puts("$Revision: 1.110 $ $Date: 1999/05/03 19:09:54 $\n");
1513+
puts("$Revision: 1.111 $ $Date: 1999/05/09 23:31:47 $\n");
15431514
}
15441515

15451516
/* ----------------

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