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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 inner relations, so it should be evaluated as the condition in the upper-level WHERE clause. The signatures of deparseFromExprForRel() and deparseRangeTblRef() are revised so that they can add conditions to the upper level. PgFdwRelationInfo now has a hidden_subquery_rels field, referencing the relids used in the inner parts of semi-join. They can't be referred to from upper relations and should be used internally for equivalence member searches. The planner can create semi-join, which refers to inner rel vars in its target list. However, we deparse semi-join as an exists() subquery. So we skip the case when the target list references to inner rel of semi-join. Author: Alexander Pyhalov Reviewed-by: Ashutosh Bapat, Ian Lawrence Barwick, Yuuki Fujii, Tomas Vondra Discussion: https://postgr.es/m/c9e2a757cf3ac2333714eaf83a9cc184@postgrespro.ru
This commit is contained in:
Alexander Korotkov
@ -180,11 +180,15 @@ static void appendConditions(List *exprs, deparse_expr_cxt *context);
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static void deparseFromExprForRel(StringInfo buf, PlannerInfo *root,
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RelOptInfo *foreignrel, bool use_alias,
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Index ignore_rel, List **ignore_conds,
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List **additional_conds,
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List **params_list);
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static void appendWhereClause(List *exprs, List *additional_conds,
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deparse_expr_cxt *context);
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static void deparseFromExpr(List *quals, deparse_expr_cxt *context);
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static void deparseRangeTblRef(StringInfo buf, PlannerInfo *root,
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RelOptInfo *foreignrel, bool make_subquery,
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Index ignore_rel, List **ignore_conds, List **params_list);
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Index ignore_rel, List **ignore_conds,
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List **additional_conds, List **params_list);
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static void deparseAggref(Aggref *node, deparse_expr_cxt *context);
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static void appendGroupByClause(List *tlist, deparse_expr_cxt *context);
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static void appendOrderBySuffix(Oid sortop, Oid sortcoltype, bool nulls_first,
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@ -1370,6 +1374,7 @@ deparseFromExpr(List *quals, deparse_expr_cxt *context)
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{
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StringInfo buf = context->buf;
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RelOptInfo *scanrel = context->scanrel;
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List *additional_conds = NIL;
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/* For upper relations, scanrel must be either a joinrel or a baserel */
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Assert(!IS_UPPER_REL(context->foreignrel) ||
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@ -1379,14 +1384,11 @@ deparseFromExpr(List *quals, deparse_expr_cxt *context)
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appendStringInfoString(buf, " FROM ");
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deparseFromExprForRel(buf, context->root, scanrel,
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(bms_membership(scanrel->relids) == BMS_MULTIPLE),
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(Index) 0, NULL, context->params_list);
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/* Construct WHERE clause */
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if (quals != NIL)
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{
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appendStringInfoString(buf, " WHERE ");
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appendConditions(quals, context);
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}
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(Index) 0, NULL, &additional_conds,
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context->params_list);
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appendWhereClause(quals, additional_conds, context);
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if (additional_conds != NIL)
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list_free_deep(additional_conds);
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}
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/*
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@ -1598,6 +1600,42 @@ appendConditions(List *exprs, deparse_expr_cxt *context)
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reset_transmission_modes(nestlevel);
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}
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/*
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* Append WHERE clause, containing conditions from exprs and additional_conds,
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* to context->buf.
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*/
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static void
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appendWhereClause(List *exprs, List *additional_conds, deparse_expr_cxt *context)
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{
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StringInfo buf = context->buf;
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bool need_and = false;
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ListCell *lc;
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if (exprs != NIL || additional_conds != NIL)
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appendStringInfoString(buf, " WHERE ");
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/*
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* If there are some filters, append them.
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*/
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if (exprs != NIL)
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{
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appendConditions(exprs, context);
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need_and = true;
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}
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/*
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* If there are some EXISTS conditions, coming from SEMI-JOINS, append
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* them.
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*/
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foreach(lc, additional_conds)
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{
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if (need_and)
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appendStringInfoString(buf, " AND ");
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appendStringInfoString(buf, (char *) lfirst(lc));
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need_and = true;
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}
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}
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/* Output join name for given join type */
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const char *
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get_jointype_name(JoinType jointype)
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@ -1616,6 +1654,9 @@ get_jointype_name(JoinType jointype)
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case JOIN_FULL:
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return "FULL";
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case JOIN_SEMI:
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return "SEMI";
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default:
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/* Shouldn't come here, but protect from buggy code. */
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elog(ERROR, "unsupported join type %d", jointype);
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@ -1712,11 +1753,14 @@ deparseSubqueryTargetList(deparse_expr_cxt *context)
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* of DELETE; it deparses the join relation as if the relation never contained
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* the target relation, and creates a List of conditions to be deparsed into
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* the top-level WHERE clause, which is returned to *ignore_conds.
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*
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* 'additional_conds' is a pointer to a list of strings to be appended to
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* the WHERE clause, coming from lower-level SEMI-JOINs.
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*/
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static void
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deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
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bool use_alias, Index ignore_rel, List **ignore_conds,
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List **params_list)
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List **additional_conds, List **params_list)
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{
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PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
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@ -1728,6 +1772,8 @@ deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
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RelOptInfo *innerrel = fpinfo->innerrel;
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bool outerrel_is_target = false;
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bool innerrel_is_target = false;
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List *additional_conds_i = NIL;
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List *additional_conds_o = NIL;
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if (ignore_rel > 0 && bms_is_member(ignore_rel, foreignrel->relids))
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{
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@ -1764,7 +1810,8 @@ deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
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initStringInfo(&join_sql_o);
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deparseRangeTblRef(&join_sql_o, root, outerrel,
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fpinfo->make_outerrel_subquery,
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ignore_rel, ignore_conds, params_list);
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ignore_rel, ignore_conds, &additional_conds_o,
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params_list);
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/*
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* If inner relation is the target relation, skip deparsing it.
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@ -1780,6 +1827,12 @@ deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
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Assert(fpinfo->jointype == JOIN_INNER);
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Assert(fpinfo->joinclauses == NIL);
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appendBinaryStringInfo(buf, join_sql_o.data, join_sql_o.len);
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/* Pass EXISTS conditions to upper level */
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if (additional_conds_o != NIL)
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{
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Assert(*additional_conds == NIL);
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*additional_conds = additional_conds_o;
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}
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return;
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}
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}
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@ -1790,7 +1843,54 @@ deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
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initStringInfo(&join_sql_i);
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deparseRangeTblRef(&join_sql_i, root, innerrel,
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fpinfo->make_innerrel_subquery,
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ignore_rel, ignore_conds, params_list);
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ignore_rel, ignore_conds, &additional_conds_i,
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params_list);
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/*
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* SEMI-JOIN is deparsed as the EXISTS subquery. It references
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* outer and inner relations, so it should be evaluated as the
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* condition in the upper-level WHERE clause. We deparse the
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* condition and pass it to upper level callers as an
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* additional_conds list. Upper level callers are responsible for
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* inserting conditions from the list where appropriate.
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*/
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if (fpinfo->jointype == JOIN_SEMI)
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{
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deparse_expr_cxt context;
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StringInfoData str;
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/* Construct deparsed condition from this SEMI-JOIN */
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initStringInfo(&str);
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appendStringInfo(&str, "EXISTS (SELECT NULL FROM %s",
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join_sql_i.data);
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context.buf = &str;
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context.foreignrel = foreignrel;
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context.scanrel = foreignrel;
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context.root = root;
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context.params_list = params_list;
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/*
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* Append SEMI-JOIN clauses and EXISTS conditions from lower
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* levels to the current EXISTS subquery
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*/
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appendWhereClause(fpinfo->joinclauses, additional_conds_i, &context);
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/*
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* EXISTS conditions, coming from lower join levels, have just
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* been processed.
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*/
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if (additional_conds_i != NIL)
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{
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list_free_deep(additional_conds_i);
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additional_conds_i = NIL;
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}
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/* Close parentheses for EXISTS subquery */
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appendStringInfo(&str, ")");
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*additional_conds = lappend(*additional_conds, str.data);
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}
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/*
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* If outer relation is the target relation, skip deparsing it.
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@ -1801,6 +1901,12 @@ deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
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Assert(fpinfo->jointype == JOIN_INNER);
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Assert(fpinfo->joinclauses == NIL);
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appendBinaryStringInfo(buf, join_sql_i.data, join_sql_i.len);
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/* Pass EXISTS conditions to the upper call */
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if (additional_conds_i != NIL)
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{
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Assert(*additional_conds == NIL);
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*additional_conds = additional_conds_i;
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}
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return;
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}
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}
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@ -1809,33 +1915,65 @@ deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
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Assert(!outerrel_is_target && !innerrel_is_target);
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/*
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* For a join relation FROM clause entry is deparsed as
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*
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* ((outer relation) <join type> (inner relation) ON (joinclauses))
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* For semijoin FROM clause is deparsed as an outer relation. An inner
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* relation and join clauses are converted to EXISTS condition and
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* passed to the upper level.
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*/
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appendStringInfo(buf, "(%s %s JOIN %s ON ", join_sql_o.data,
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get_jointype_name(fpinfo->jointype), join_sql_i.data);
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/* Append join clause; (TRUE) if no join clause */
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if (fpinfo->joinclauses)
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if (fpinfo->jointype == JOIN_SEMI)
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{
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deparse_expr_cxt context;
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context.buf = buf;
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context.foreignrel = foreignrel;
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context.scanrel = foreignrel;
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context.root = root;
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context.params_list = params_list;
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appendStringInfoChar(buf, '(');
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appendConditions(fpinfo->joinclauses, &context);
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appendStringInfoChar(buf, ')');
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appendStringInfo(buf, "%s", join_sql_o.data);
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}
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else
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appendStringInfoString(buf, "(TRUE)");
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{
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/*
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* For a join relation FROM clause, entry is deparsed as
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*
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* ((outer relation) <join type> (inner relation) ON
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* (joinclauses))
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*/
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appendStringInfo(buf, "(%s %s JOIN %s ON ", join_sql_o.data,
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get_jointype_name(fpinfo->jointype), join_sql_i.data);
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/* End the FROM clause entry. */
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appendStringInfoChar(buf, ')');
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/* Append join clause; (TRUE) if no join clause */
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if (fpinfo->joinclauses)
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{
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deparse_expr_cxt context;
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context.buf = buf;
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context.foreignrel = foreignrel;
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context.scanrel = foreignrel;
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context.root = root;
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context.params_list = params_list;
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appendStringInfoChar(buf, '(');
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appendConditions(fpinfo->joinclauses, &context);
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appendStringInfoChar(buf, ')');
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}
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else
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appendStringInfoString(buf, "(TRUE)");
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/* End the FROM clause entry. */
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appendStringInfoChar(buf, ')');
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}
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/*
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* Construct additional_conds to be passed to the upper caller from
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* current level additional_conds and additional_conds, coming from
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* inner and outer rels.
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*/
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if (additional_conds_o != NIL)
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{
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*additional_conds = list_concat(*additional_conds,
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additional_conds_o);
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list_free(additional_conds_o);
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}
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if (additional_conds_i != NIL)
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{
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*additional_conds = list_concat(*additional_conds,
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additional_conds_i);
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list_free(additional_conds_i);
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}
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}
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else
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{
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@ -1863,11 +2001,13 @@ deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
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/*
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* Append FROM clause entry for the given relation into buf.
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* Conditions from lower-level SEMI-JOINs are appended to additional_conds
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* and should be added to upper level WHERE clause.
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*/
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static void
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deparseRangeTblRef(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
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bool make_subquery, Index ignore_rel, List **ignore_conds,
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List **params_list)
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List **additional_conds, List **params_list)
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{
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PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
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@ -1925,7 +2065,8 @@ deparseRangeTblRef(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
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}
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else
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deparseFromExprForRel(buf, root, foreignrel, true, ignore_rel,
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ignore_conds, params_list);
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ignore_conds, additional_conds,
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params_list);
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}
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/*
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@ -2148,6 +2289,7 @@ deparseDirectUpdateSql(StringInfo buf, PlannerInfo *root,
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RangeTblEntry *rte = planner_rt_fetch(rtindex, root);
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ListCell *lc,
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*lc2;
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List *additional_conds = NIL;
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/* Set up context struct for recursion */
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context.root = root;
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@ -2189,17 +2331,17 @@ deparseDirectUpdateSql(StringInfo buf, PlannerInfo *root,
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{
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List *ignore_conds = NIL;
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appendStringInfoString(buf, " FROM ");
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deparseFromExprForRel(buf, root, foreignrel, true, rtindex,
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&ignore_conds, params_list);
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&ignore_conds, &additional_conds, params_list);
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remote_conds = list_concat(remote_conds, ignore_conds);
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}
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if (remote_conds)
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{
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appendStringInfoString(buf, " WHERE ");
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appendConditions(remote_conds, &context);
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}
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appendWhereClause(remote_conds, additional_conds, &context);
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if (additional_conds != NIL)
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list_free_deep(additional_conds);
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if (foreignrel->reloptkind == RELOPT_JOINREL)
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deparseExplicitTargetList(returningList, true, retrieved_attrs,
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@ -2255,6 +2397,7 @@ deparseDirectDeleteSql(StringInfo buf, PlannerInfo *root,
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List **retrieved_attrs)
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{
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deparse_expr_cxt context;
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List *additional_conds = NIL;
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/* Set up context struct for recursion */
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context.root = root;
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@ -2274,15 +2417,14 @@ deparseDirectDeleteSql(StringInfo buf, PlannerInfo *root,
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appendStringInfoString(buf, " USING ");
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deparseFromExprForRel(buf, root, foreignrel, true, rtindex,
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&ignore_conds, params_list);
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&ignore_conds, &additional_conds, params_list);
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remote_conds = list_concat(remote_conds, ignore_conds);
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}
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if (remote_conds)
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{
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appendStringInfoString(buf, " WHERE ");
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appendConditions(remote_conds, &context);
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}
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appendWhereClause(remote_conds, additional_conds, &context);
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if (additional_conds != NIL)
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list_free_deep(additional_conds);
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if (foreignrel->reloptkind == RELOPT_JOINREL)
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deparseExplicitTargetList(returningList, true, retrieved_attrs,
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