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Commit824dbea

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Add support for deparsing semi-joins to contrib/postgres_fdw
SEMI-JOIN is deparsed as the EXISTS subquery. It references outer and innerrelations, so it should be evaluated as the condition in the upper-level WHEREclause. The signatures of deparseFromExprForRel() and deparseRangeTblRef() arerevised so that they can add conditions to the upper level.PgFdwRelationInfo now has a hidden_subquery_rels field, referencing the relidsused in the inner parts of semi-join. They can't be referred to from upperrelations and should be used internally for equivalence member searches.The planner can create semi-join, which refers to inner rel vars in its targetlist. However, we deparse semi-join as an exists() subquery. So we skip thecase when the target list references to inner rel of semi-join.Author: Alexander PyhalovReviewed-by: Ashutosh Bapat, Ian Lawrence Barwick, Yuuki Fujii, Tomas VondraDiscussion:https://postgr.es/m/c9e2a757cf3ac2333714eaf83a9cc184@postgrespro.ru
1 parent278eb13 commit824dbea

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5 files changed

+697
-81
lines changed

5 files changed

+697
-81
lines changed

‎contrib/postgres_fdw/deparse.c

Lines changed: 188 additions & 46 deletions
Original file line numberDiff line numberDiff line change
@@ -180,11 +180,15 @@ static void appendConditions(List *exprs, deparse_expr_cxt *context);
180180
staticvoiddeparseFromExprForRel(StringInfobuf,PlannerInfo*root,
181181
RelOptInfo*foreignrel,booluse_alias,
182182
Indexignore_rel,List**ignore_conds,
183+
List**additional_conds,
183184
List**params_list);
185+
staticvoidappendWhereClause(List*exprs,List*additional_conds,
186+
deparse_expr_cxt*context);
184187
staticvoiddeparseFromExpr(List*quals,deparse_expr_cxt*context);
185188
staticvoiddeparseRangeTblRef(StringInfobuf,PlannerInfo*root,
186189
RelOptInfo*foreignrel,boolmake_subquery,
187-
Indexignore_rel,List**ignore_conds,List**params_list);
190+
Indexignore_rel,List**ignore_conds,
191+
List**additional_conds,List**params_list);
188192
staticvoiddeparseAggref(Aggref*node,deparse_expr_cxt*context);
189193
staticvoidappendGroupByClause(List*tlist,deparse_expr_cxt*context);
190194
staticvoidappendOrderBySuffix(Oidsortop,Oidsortcoltype,boolnulls_first,
@@ -1370,6 +1374,7 @@ deparseFromExpr(List *quals, deparse_expr_cxt *context)
13701374
{
13711375
StringInfobuf=context->buf;
13721376
RelOptInfo*scanrel=context->scanrel;
1377+
List*additional_conds=NIL;
13731378

13741379
/* For upper relations, scanrel must be either a joinrel or a baserel */
13751380
Assert(!IS_UPPER_REL(context->foreignrel)||
@@ -1379,14 +1384,11 @@ deparseFromExpr(List *quals, deparse_expr_cxt *context)
13791384
appendStringInfoString(buf," FROM ");
13801385
deparseFromExprForRel(buf,context->root,scanrel,
13811386
(bms_membership(scanrel->relids)==BMS_MULTIPLE),
1382-
(Index)0,NULL,context->params_list);
1383-
1384-
/* Construct WHERE clause */
1385-
if (quals!=NIL)
1386-
{
1387-
appendStringInfoString(buf," WHERE ");
1388-
appendConditions(quals,context);
1389-
}
1387+
(Index)0,NULL,&additional_conds,
1388+
context->params_list);
1389+
appendWhereClause(quals,additional_conds,context);
1390+
if (additional_conds!=NIL)
1391+
list_free_deep(additional_conds);
13901392
}
13911393

13921394
/*
@@ -1598,6 +1600,42 @@ appendConditions(List *exprs, deparse_expr_cxt *context)
15981600
reset_transmission_modes(nestlevel);
15991601
}
16001602

1603+
/*
1604+
* Append WHERE clause, containing conditions from exprs and additional_conds,
1605+
* to context->buf.
1606+
*/
1607+
staticvoid
1608+
appendWhereClause(List*exprs,List*additional_conds,deparse_expr_cxt*context)
1609+
{
1610+
StringInfobuf=context->buf;
1611+
boolneed_and= false;
1612+
ListCell*lc;
1613+
1614+
if (exprs!=NIL||additional_conds!=NIL)
1615+
appendStringInfoString(buf," WHERE ");
1616+
1617+
/*
1618+
* If there are some filters, append them.
1619+
*/
1620+
if (exprs!=NIL)
1621+
{
1622+
appendConditions(exprs,context);
1623+
need_and= true;
1624+
}
1625+
1626+
/*
1627+
* If there are some EXISTS conditions, coming from SEMI-JOINS, append
1628+
* them.
1629+
*/
1630+
foreach(lc,additional_conds)
1631+
{
1632+
if (need_and)
1633+
appendStringInfoString(buf," AND ");
1634+
appendStringInfoString(buf, (char*)lfirst(lc));
1635+
need_and= true;
1636+
}
1637+
}
1638+
16011639
/* Output join name for given join type */
16021640
constchar*
16031641
get_jointype_name(JoinTypejointype)
@@ -1616,6 +1654,9 @@ get_jointype_name(JoinType jointype)
16161654
caseJOIN_FULL:
16171655
return"FULL";
16181656

1657+
caseJOIN_SEMI:
1658+
return"SEMI";
1659+
16191660
default:
16201661
/* Shouldn't come here, but protect from buggy code. */
16211662
elog(ERROR,"unsupported join type %d",jointype);
@@ -1712,11 +1753,14 @@ deparseSubqueryTargetList(deparse_expr_cxt *context)
17121753
* of DELETE; it deparses the join relation as if the relation never contained
17131754
* the target relation, and creates a List of conditions to be deparsed into
17141755
* the top-level WHERE clause, which is returned to *ignore_conds.
1756+
*
1757+
* 'additional_conds' is a pointer to a list of strings to be appended to
1758+
* the WHERE clause, coming from lower-level SEMI-JOINs.
17151759
*/
17161760
staticvoid
17171761
deparseFromExprForRel(StringInfobuf,PlannerInfo*root,RelOptInfo*foreignrel,
17181762
booluse_alias,Indexignore_rel,List**ignore_conds,
1719-
List**params_list)
1763+
List**additional_conds,List**params_list)
17201764
{
17211765
PgFdwRelationInfo*fpinfo= (PgFdwRelationInfo*)foreignrel->fdw_private;
17221766

@@ -1728,6 +1772,8 @@ deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
17281772
RelOptInfo*innerrel=fpinfo->innerrel;
17291773
boolouterrel_is_target= false;
17301774
boolinnerrel_is_target= false;
1775+
List*additional_conds_i=NIL;
1776+
List*additional_conds_o=NIL;
17311777

17321778
if (ignore_rel>0&&bms_is_member(ignore_rel,foreignrel->relids))
17331779
{
@@ -1764,7 +1810,8 @@ deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
17641810
initStringInfo(&join_sql_o);
17651811
deparseRangeTblRef(&join_sql_o,root,outerrel,
17661812
fpinfo->make_outerrel_subquery,
1767-
ignore_rel,ignore_conds,params_list);
1813+
ignore_rel,ignore_conds,&additional_conds_o,
1814+
params_list);
17681815

17691816
/*
17701817
* If inner relation is the target relation, skip deparsing it.
@@ -1780,6 +1827,12 @@ deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
17801827
Assert(fpinfo->jointype==JOIN_INNER);
17811828
Assert(fpinfo->joinclauses==NIL);
17821829
appendBinaryStringInfo(buf,join_sql_o.data,join_sql_o.len);
1830+
/* Pass EXISTS conditions to upper level */
1831+
if (additional_conds_o!=NIL)
1832+
{
1833+
Assert(*additional_conds==NIL);
1834+
*additional_conds=additional_conds_o;
1835+
}
17831836
return;
17841837
}
17851838
}
@@ -1790,7 +1843,54 @@ deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
17901843
initStringInfo(&join_sql_i);
17911844
deparseRangeTblRef(&join_sql_i,root,innerrel,
17921845
fpinfo->make_innerrel_subquery,
1793-
ignore_rel,ignore_conds,params_list);
1846+
ignore_rel,ignore_conds,&additional_conds_i,
1847+
params_list);
1848+
1849+
/*
1850+
* SEMI-JOIN is deparsed as the EXISTS subquery. It references
1851+
* outer and inner relations, so it should be evaluated as the
1852+
* condition in the upper-level WHERE clause. We deparse the
1853+
* condition and pass it to upper level callers as an
1854+
* additional_conds list. Upper level callers are responsible for
1855+
* inserting conditions from the list where appropriate.
1856+
*/
1857+
if (fpinfo->jointype==JOIN_SEMI)
1858+
{
1859+
deparse_expr_cxtcontext;
1860+
StringInfoDatastr;
1861+
1862+
/* Construct deparsed condition from this SEMI-JOIN */
1863+
initStringInfo(&str);
1864+
appendStringInfo(&str,"EXISTS (SELECT NULL FROM %s",
1865+
join_sql_i.data);
1866+
1867+
context.buf=&str;
1868+
context.foreignrel=foreignrel;
1869+
context.scanrel=foreignrel;
1870+
context.root=root;
1871+
context.params_list=params_list;
1872+
1873+
/*
1874+
* Append SEMI-JOIN clauses and EXISTS conditions from lower
1875+
* levels to the current EXISTS subquery
1876+
*/
1877+
appendWhereClause(fpinfo->joinclauses,additional_conds_i,&context);
1878+
1879+
/*
1880+
* EXISTS conditions, coming from lower join levels, have just
1881+
* been processed.
1882+
*/
1883+
if (additional_conds_i!=NIL)
1884+
{
1885+
list_free_deep(additional_conds_i);
1886+
additional_conds_i=NIL;
1887+
}
1888+
1889+
/* Close parentheses for EXISTS subquery */
1890+
appendStringInfo(&str,")");
1891+
1892+
*additional_conds=lappend(*additional_conds,str.data);
1893+
}
17941894

17951895
/*
17961896
* If outer relation is the target relation, skip deparsing it.
@@ -1801,6 +1901,12 @@ deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
18011901
Assert(fpinfo->jointype==JOIN_INNER);
18021902
Assert(fpinfo->joinclauses==NIL);
18031903
appendBinaryStringInfo(buf,join_sql_i.data,join_sql_i.len);
1904+
/* Pass EXISTS conditions to the upper call */
1905+
if (additional_conds_i!=NIL)
1906+
{
1907+
Assert(*additional_conds==NIL);
1908+
*additional_conds=additional_conds_i;
1909+
}
18041910
return;
18051911
}
18061912
}
@@ -1809,33 +1915,65 @@ deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
18091915
Assert(!outerrel_is_target&& !innerrel_is_target);
18101916

18111917
/*
1812-
* Fora join relationFROM clauseentryis deparsed as
1813-
*
1814-
*((outer relation) <join type> (inner relation) ON (joinclauses))
1918+
* ForsemijoinFROM clause is deparsed as an outer relation. An inner
1919+
* relation and join clauses are converted to EXISTS condition and
1920+
*passed to the upper level.
18151921
*/
1816-
appendStringInfo(buf,"(%s %s JOIN %s ON ",join_sql_o.data,
1817-
get_jointype_name(fpinfo->jointype),join_sql_i.data);
1818-
1819-
/* Append join clause; (TRUE) if no join clause */
1820-
if (fpinfo->joinclauses)
1922+
if (fpinfo->jointype==JOIN_SEMI)
18211923
{
1822-
deparse_expr_cxtcontext;
1924+
appendStringInfo(buf,"%s",join_sql_o.data);
1925+
}
1926+
else
1927+
{
1928+
/*
1929+
* For a join relation FROM clause, entry is deparsed as
1930+
*
1931+
* ((outer relation) <join type> (inner relation) ON
1932+
* (joinclauses))
1933+
*/
1934+
appendStringInfo(buf,"(%s %s JOIN %s ON ",join_sql_o.data,
1935+
get_jointype_name(fpinfo->jointype),join_sql_i.data);
18231936

1824-
context.buf=buf;
1825-
context.foreignrel=foreignrel;
1826-
context.scanrel=foreignrel;
1827-
context.root=root;
1828-
context.params_list=params_list;
1937+
/* Append join clause; (TRUE) if no join clause */
1938+
if (fpinfo->joinclauses)
1939+
{
1940+
deparse_expr_cxtcontext;
18291941

1830-
appendStringInfoChar(buf,'(');
1831-
appendConditions(fpinfo->joinclauses,&context);
1942+
context.buf=buf;
1943+
context.foreignrel=foreignrel;
1944+
context.scanrel=foreignrel;
1945+
context.root=root;
1946+
context.params_list=params_list;
1947+
1948+
appendStringInfoChar(buf,'(');
1949+
appendConditions(fpinfo->joinclauses,&context);
1950+
appendStringInfoChar(buf,')');
1951+
}
1952+
else
1953+
appendStringInfoString(buf,"(TRUE)");
1954+
1955+
/* End the FROM clause entry. */
18321956
appendStringInfoChar(buf,')');
18331957
}
1834-
else
1835-
appendStringInfoString(buf,"(TRUE)");
18361958

1837-
/* End the FROM clause entry. */
1838-
appendStringInfoChar(buf,')');
1959+
/*
1960+
* Construct additional_conds to be passed to the upper caller from
1961+
* current level additional_conds and additional_conds, coming from
1962+
* inner and outer rels.
1963+
*/
1964+
if (additional_conds_o!=NIL)
1965+
{
1966+
*additional_conds=list_concat(*additional_conds,
1967+
additional_conds_o);
1968+
list_free(additional_conds_o);
1969+
}
1970+
1971+
if (additional_conds_i!=NIL)
1972+
{
1973+
*additional_conds=list_concat(*additional_conds,
1974+
additional_conds_i);
1975+
list_free(additional_conds_i);
1976+
}
18391977
}
18401978
else
18411979
{
@@ -1863,11 +2001,13 @@ deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
18632001

18642002
/*
18652003
* Append FROM clause entry for the given relation into buf.
2004+
* Conditions from lower-level SEMI-JOINs are appended to additional_conds
2005+
* and should be added to upper level WHERE clause.
18662006
*/
18672007
staticvoid
18682008
deparseRangeTblRef(StringInfobuf,PlannerInfo*root,RelOptInfo*foreignrel,
18692009
boolmake_subquery,Indexignore_rel,List**ignore_conds,
1870-
List**params_list)
2010+
List**additional_conds,List**params_list)
18712011
{
18722012
PgFdwRelationInfo*fpinfo= (PgFdwRelationInfo*)foreignrel->fdw_private;
18732013

@@ -1925,7 +2065,8 @@ deparseRangeTblRef(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
19252065
}
19262066
else
19272067
deparseFromExprForRel(buf,root,foreignrel, true,ignore_rel,
1928-
ignore_conds,params_list);
2068+
ignore_conds,additional_conds,
2069+
params_list);
19292070
}
19302071

19312072
/*
@@ -2148,6 +2289,7 @@ deparseDirectUpdateSql(StringInfo buf, PlannerInfo *root,
21482289
RangeTblEntry*rte=planner_rt_fetch(rtindex,root);
21492290
ListCell*lc,
21502291
*lc2;
2292+
List*additional_conds=NIL;
21512293

21522294
/* Set up context struct for recursion */
21532295
context.root=root;
@@ -2189,17 +2331,17 @@ deparseDirectUpdateSql(StringInfo buf, PlannerInfo *root,
21892331
{
21902332
List*ignore_conds=NIL;
21912333

2334+
21922335
appendStringInfoString(buf," FROM ");
21932336
deparseFromExprForRel(buf,root,foreignrel, true,rtindex,
2194-
&ignore_conds,params_list);
2337+
&ignore_conds,&additional_conds,params_list);
21952338
remote_conds=list_concat(remote_conds,ignore_conds);
21962339
}
21972340

2198-
if (remote_conds)
2199-
{
2200-
appendStringInfoString(buf," WHERE ");
2201-
appendConditions(remote_conds,&context);
2202-
}
2341+
appendWhereClause(remote_conds,additional_conds,&context);
2342+
2343+
if (additional_conds!=NIL)
2344+
list_free_deep(additional_conds);
22032345

22042346
if (foreignrel->reloptkind==RELOPT_JOINREL)
22052347
deparseExplicitTargetList(returningList, true,retrieved_attrs,
@@ -2255,6 +2397,7 @@ deparseDirectDeleteSql(StringInfo buf, PlannerInfo *root,
22552397
List**retrieved_attrs)
22562398
{
22572399
deparse_expr_cxtcontext;
2400+
List*additional_conds=NIL;
22582401

22592402
/* Set up context struct for recursion */
22602403
context.root=root;
@@ -2274,15 +2417,14 @@ deparseDirectDeleteSql(StringInfo buf, PlannerInfo *root,
22742417

22752418
appendStringInfoString(buf," USING ");
22762419
deparseFromExprForRel(buf,root,foreignrel, true,rtindex,
2277-
&ignore_conds,params_list);
2420+
&ignore_conds,&additional_conds,params_list);
22782421
remote_conds=list_concat(remote_conds,ignore_conds);
22792422
}
22802423

2281-
if (remote_conds)
2282-
{
2283-
appendStringInfoString(buf," WHERE ");
2284-
appendConditions(remote_conds,&context);
2285-
}
2424+
appendWhereClause(remote_conds,additional_conds,&context);
2425+
2426+
if (additional_conds!=NIL)
2427+
list_free_deep(additional_conds);
22862428

22872429
if (foreignrel->reloptkind==RELOPT_JOINREL)
22882430
deparseExplicitTargetList(returningList, true,retrieved_attrs,

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