From 9c9fa2e37fc62ddcd8dc6176306d74b7e219fd26 Mon Sep 17 00:00:00 2001 From: Alexander Pyhalov Date: Thu, 22 Jul 2021 11:42:16 +0300 Subject: [PATCH] Allow pushing CASE expression to foreign server --- contrib/postgres_fdw/deparse.c | 150 ++++++++++++++ .../postgres_fdw/expected/postgres_fdw.out | 184 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 63 ++++++ 3 files changed, 397 insertions(+) diff --git a/contrib/postgres_fdw/deparse.c b/contrib/postgres_fdw/deparse.c index 31919fda8c6..df1aaf8e713 100644 --- a/contrib/postgres_fdw/deparse.c +++ b/contrib/postgres_fdw/deparse.c @@ -186,6 +186,8 @@ static void appendFunctionName(Oid funcid, deparse_expr_cxt *context); static Node *deparseSortGroupClause(Index ref, List *tlist, bool force_colno, deparse_expr_cxt *context); +static void deparseCaseExpr(CaseExpr *node, deparse_expr_cxt *context); + /* * Helper functions */ @@ -627,6 +629,105 @@ foreign_expr_walker(Node *node, state = FDW_COLLATE_NONE; } break; + case T_CaseExpr: + { + ListCell *lc; + foreign_loc_cxt tmp_cxt; + CaseExpr *ce = (CaseExpr *) node; + + /* + * case arg expression collation doesn't affect result + * collation + */ + tmp_cxt.collation = InvalidOid; + tmp_cxt.state = FDW_COLLATE_NONE; + if (ce->arg && !foreign_expr_walker((Node *) ce->arg, glob_cxt, &tmp_cxt)) + return false; + + /* Recurse to case clause subexpressions. */ + foreach(lc, ce->args) + { + CaseWhen *cw = lfirst_node(CaseWhen, lc); + Node *whenExpr = (Node *) cw->expr; + + /* + * The parser should have produced WHEN clauses of the + * form "CaseTestExpr = RHS", possibly with an implicit + * coercion inserted above the CaseTestExpr. However in an + * expression that's been through the optimizer, the WHEN + * clause could be almost anything (since the equality + * operator could have been expanded into an inline + * function). In this case forbid pushdown. + */ + + if (ce->arg) + { + List *whenExprArgs; + + if (!IsA(whenExpr, OpExpr)) + return false; + + whenExprArgs = ((OpExpr *) whenExpr)->args; + + if ((list_length(whenExprArgs) != 2) || + !IsA(strip_implicit_coercions(linitial(whenExprArgs)), CaseTestExpr)) + return false; + } + + /* + * case when expression collation doesn't affect result + * collation + */ + tmp_cxt.collation = InvalidOid; + tmp_cxt.state = FDW_COLLATE_NONE; + /* Recurse to case clause expression. */ + if (!foreign_expr_walker((Node *) cw->expr, + glob_cxt, &tmp_cxt)) + return false; + + /* Recurse to result expression. */ + if (!foreign_expr_walker((Node *) cw->result, + glob_cxt, &inner_cxt)) + return false; + } + + if (!foreign_expr_walker((Node *) ce->defresult, glob_cxt, &inner_cxt)) + return false; + + /* + * Collation rule is same as for function nodes. + */ + collation = ce->casecollid; + if (collation == InvalidOid) + state = FDW_COLLATE_NONE; + else if (inner_cxt.state == FDW_COLLATE_SAFE && + collation == inner_cxt.collation) + state = FDW_COLLATE_SAFE; + else if (collation == DEFAULT_COLLATION_OID) + state = FDW_COLLATE_NONE; + else + state = FDW_COLLATE_UNSAFE; + } + break; + case T_CaseTestExpr: + { + CaseTestExpr *c = (CaseTestExpr *) node; + + /* + * Collation rule is same as for function nodes. + */ + collation = c->collation; + if (collation == InvalidOid) + state = FDW_COLLATE_NONE; + else if (inner_cxt.state == FDW_COLLATE_SAFE && + collation == inner_cxt.collation) + state = FDW_COLLATE_SAFE; + else if (collation == DEFAULT_COLLATION_OID) + state = FDW_COLLATE_NONE; + else + state = FDW_COLLATE_UNSAFE; + } + break; case T_NullTest: { NullTest *nt = (NullTest *) node; @@ -2462,6 +2563,9 @@ deparseExpr(Expr *node, deparse_expr_cxt *context) case T_Aggref: deparseAggref((Aggref *) node, context); break; + case T_CaseExpr: + deparseCaseExpr((CaseExpr *) node, context); + break; default: elog(ERROR, "unsupported expression type for deparse: %d", (int) nodeTag(node)); @@ -3007,6 +3111,52 @@ deparseNullTest(NullTest *node, deparse_expr_cxt *context) } } +/* + * Deparse CASE expression + */ +static void +deparseCaseExpr(CaseExpr *node, deparse_expr_cxt *context) +{ + StringInfo buf = context->buf; + ListCell *lc = NULL; + + appendStringInfoString(buf, "(CASE"); + + /* If this is a CASE arg WHEN clause process arg first */ + if (node->arg != NULL) + { + appendStringInfoString(buf, " "); + deparseExpr(node->arg, context); + } + + /* Add each condition/result of the CASE clause */ + foreach(lc, node->args) + { + CaseWhen *whenclause = (CaseWhen *) lfirst(lc); + + /* WHEN */ + appendStringInfoString(buf, " WHEN "); + if (node->arg == NULL) /* CASE WHEN */ + deparseExpr(whenclause->expr, context); + else /* CASE arg WHEN */ + deparseExpr(lsecond(((OpExpr *) whenclause->expr)->args), context); + + /* THEN */ + appendStringInfoString(buf, " THEN "); + deparseExpr(whenclause->result, context); + } + + /* add ELSE if needed */ + if (node->defresult != NULL) + { + appendStringInfoString(buf, " ELSE "); + deparseExpr(node->defresult, context); + } + + /* append END */ + appendStringInfoString(buf, " END)"); +} + /* * Deparse ARRAY[...] construct. */ diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index ed25e7a743f..9a966b73cc1 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -5561,6 +5561,190 @@ UPDATE ft2 d SET c2 = CASE WHEN random() >= 0 THEN d.c2 ELSE 0 END UPDATE ft2 d SET c2 = CASE WHEN random() >= 0 THEN d.c2 ELSE 0 END FROM ft2 AS t WHERE d.c1 = t.c1 AND d.c1 > 1000; +-- Test CASE pushdown +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE ft2 d SET c2 = CASE WHEN c2 > 0 THEN c2 ELSE 0 END +WHERE c1 > 1000; + QUERY PLAN +---------------------------------------------------------------------------------------------------------------- + Update on public.ft2 d + -> Foreign Update on public.ft2 d + Remote SQL: UPDATE "S 1"."T 1" SET c2 = (CASE WHEN (c2 > 0) THEN c2 ELSE 0 END) WHERE (("C 1" > 1000)) +(3 rows) + +UPDATE ft2 d SET c2 = CASE WHEN c2 > 0 THEN c2 ELSE 0 END +WHERE c1 > 1000; +-- CASE in WHERE clause +EXPLAIN (VERBOSE, COSTS OFF) +SELECT c1,c2,c3 FROM ft2 WHERE CASE WHEN c2 > 600 THEN c2 END > 500 ORDER BY c1; + QUERY PLAN +--------------------------------------------------------------------------------------------------------------------------------------------------------- + Foreign Scan on public.ft2 + Output: c1, c2, c3 + Remote SQL: SELECT "C 1", c2, c3 FROM "S 1"."T 1" WHERE (((CASE WHEN (c2 > 600) THEN c2 ELSE NULL::integer END) > 500)) ORDER BY "C 1" ASC NULLS LAST +(3 rows) + +SELECT c1,c2,c3 FROM ft2 WHERE CASE WHEN c2 > 600 THEN c2 END > 500 ORDER BY c1; + c1 | c2 | c3 +------+-----+-------------------- + 1009 | 609 | 0000900009_update9 + 1019 | 609 | 0001900019_update9 +(2 rows) + +-- Nested CASE +EXPLAIN (VERBOSE, COSTS OFF) +SELECT c1,c2,c3 FROM ft2 WHERE CASE CASE WHEN c2 > 0 THEN c2 END WHEN 100 THEN 601 WHEN c2 THEN c2 ELSE 0 END > 600 ORDER BY c1; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- + Foreign Scan on public.ft2 + Output: c1, c2, c3 + Remote SQL: SELECT "C 1", c2, c3 FROM "S 1"."T 1" WHERE (((CASE (CASE WHEN (c2 > 0) THEN c2 ELSE NULL::integer END) WHEN 100 THEN 601 WHEN c2 THEN c2 ELSE 0 END) > 600)) ORDER BY "C 1" ASC NULLS LAST +(3 rows) + +SELECT c1,c2,c3 FROM ft2 WHERE CASE CASE WHEN c2 > 0 THEN c2 END WHEN 100 THEN 601 WHEN c2 THEN c2 ELSE 0 END > 600 ORDER BY c1; + c1 | c2 | c3 +------+-----+-------------------- + 1009 | 609 | 0000900009_update9 + 1010 | 100 | 0001000010 + 1019 | 609 | 0001900019_update9 + 1020 | 100 | 0002000020 +(4 rows) + +-- Aggregate function with CASE clause, both must be pushed down +EXPLAIN (VERBOSE, COSTS OFF) +SELECT sum(CASE WHEN mod(c1, 4) = 0 THEN 1 ELSE 2 END) FROM ft1; + QUERY PLAN +---------------------------------------------------------------------------------------------- + Foreign Scan + Output: (sum(CASE WHEN (mod(c1, 4) = 0) THEN 1 ELSE 2 END)) + Relations: Aggregate on (public.ft1) + Remote SQL: SELECT sum((CASE WHEN (mod("C 1", 4) = 0) THEN 1 ELSE 2 END)) FROM "S 1"."T 1" +(4 rows) + +-- Same but with out ELSE clause +EXPLAIN (VERBOSE, COSTS OFF) +SELECT sum(CASE WHEN mod(c1, 4) = 0 THEN 1 END) FROM ft1; + QUERY PLAN +---------------------------------------------------------------------------------------------------------- + Foreign Scan + Output: (sum(CASE WHEN (mod(c1, 4) = 0) THEN 1 ELSE NULL::integer END)) + Relations: Aggregate on (public.ft1) + Remote SQL: SELECT sum((CASE WHEN (mod("C 1", 4) = 0) THEN 1 ELSE NULL::integer END)) FROM "S 1"."T 1" +(4 rows) + +-- Different CASE form using a function in the condition +EXPLAIN (VERBOSE, COSTS OFF) +SELECT * FROM ft1 WHERE c1 > (CASE WHEN mod(c1, 4) = 0 THEN 1 ELSE 100 END); + QUERY PLAN +----------------------------------------------------------------------------------------------------------------------------------------------- + Foreign Scan on public.ft1 + Output: c1, c2, c3, c4, c5, c6, c7, c8 + Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" > (CASE WHEN (mod("C 1", 4) = 0) THEN 1 ELSE 100 END))) +(3 rows) + +EXPLAIN (VERBOSE, COSTS OFF) +SELECT * FROM ft1 WHERE c1 > (CASE mod(c1, 4) WHEN 0 THEN 1 WHEN 2 THEN 50 ELSE 100 END); + QUERY PLAN +---------------------------------------------------------------------------------------------------------------------------------------------------------- + Foreign Scan on public.ft1 + Output: c1, c2, c3, c4, c5, c6, c7, c8 + Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" > (CASE mod("C 1", 4) WHEN 0 THEN 1 WHEN 2 THEN 50 ELSE 100 END))) +(3 rows) + +EXPLAIN (VERBOSE, COSTS OFF) +SELECT * FROM ft1 WHERE c1 > (CASE WHEN mod(c1, 4) = 0 THEN 1 WHEN mod(c1, 6) = 0 THEN 50 ELSE 100 END); + QUERY PLAN +-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- + Foreign Scan on public.ft1 + Output: c1, c2, c3, c4, c5, c6, c7, c8 + Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE (("C 1" > (CASE WHEN (mod("C 1", 4) = 0) THEN 1 WHEN (mod("C 1", 6) = 0) THEN 50 ELSE 100 END))) +(3 rows) + +EXPLAIN (VERBOSE, COSTS OFF) +SELECT * FROM ft1 WHERE substr(c3, 6) = (CASE WHEN mod(c1, 4) = 0 THEN '_trig_update' ELSE '_update' END); + QUERY PLAN +-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- + Foreign Scan on public.ft1 + Output: c1, c2, c3, c4, c5, c6, c7, c8 + Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE ((substr(c3, 6) = (CASE WHEN (mod("C 1", 4) = 0) THEN '_trig_update'::text ELSE '_update'::text END))) +(3 rows) + +-- CASE involved in a prepared statement +PREPARE pre_case_select AS SELECT * FROM ft1 WHERE substr(c3, 6) = (CASE WHEN mod(c1, 4) = 0 THEN $1 ELSE $2 END); +EXPLAIN (VERBOSE, COSTS OFF) EXECUTE pre_case_select('_trig_update', '_update'); + QUERY PLAN +-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- + Foreign Scan on public.ft1 + Output: c1, c2, c3, c4, c5, c6, c7, c8 + Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" WHERE ((substr(c3, 6) = (CASE WHEN (mod("C 1", 4) = 0) THEN '_trig_update'::text ELSE '_update'::text END))) +(3 rows) + +DEALLOCATE pre_case_select; +-- Test that CASE pushdown is not happening +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE ft2 d SET c2 = CASE WHEN random() >= 0 THEN c2 ELSE 0 END +WHERE c1 > 1000; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------------- + Update on public.ft2 d + Remote SQL: UPDATE "S 1"."T 1" SET c2 = $2 WHERE ctid = $1 + -> Foreign Scan on public.ft2 d + Output: CASE WHEN (random() >= '0'::double precision) THEN c2 ELSE 0 END, ctid, d.* + Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8, ctid FROM "S 1"."T 1" WHERE (("C 1" > 1000)) FOR UPDATE +(5 rows) + +UPDATE ft2 d SET c2 = CASE WHEN c2 > 0 THEN c2 ELSE 0 END +WHERE c1 > 1000; +EXPLAIN (VERBOSE, COSTS OFF) +SELECT * FROM ft1 WHERE substr(c3, 6) COLLATE "C" = (CASE WHEN mod(c1, 4) = 0 THEN '_trig_update' COLLATE "C" ELSE '_update' COLLATE "C" END) COLLATE "C"; + QUERY PLAN +--------------------------------------------------------------------------------------------------------------------------------------------------- + Foreign Scan on public.ft1 + Output: c1, c2, c3, c4, c5, c6, c7, c8 + Filter: ((substr(ft1.c3, 6))::text = CASE WHEN (mod(ft1.c1, 4) = 0) THEN '_trig_update'::text COLLATE "C" ELSE '_update'::text COLLATE "C" END) + Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" +(4 rows) + +EXPLAIN (VERBOSE, COSTS OFF) +SELECT * FROM ft1 WHERE c3 = (CASE random() WHEN 0 THEN '_trig_update' ELSE '_update' END); + QUERY PLAN +------------------------------------------------------------------------------------------------------------------ + Foreign Scan on public.ft1 + Output: c1, c2, c3, c4, c5, c6, c7, c8 + Filter: (ft1.c3 = CASE random() WHEN '0'::double precision THEN '_trig_update'::text ELSE '_update'::text END) + Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" +(4 rows) + +EXPLAIN (VERBOSE, COSTS OFF) +SELECT * FROM ft1 WHERE c3 = (CASE WHEN mod(c1, 4) = 0 THEN '_trig_update' ELSE '_update' COLLATE "C" END); + QUERY PLAN +---------------------------------------------------------------------------------------------------------------------------- + Foreign Scan on public.ft1 + Output: c1, c2, c3, c4, c5, c6, c7, c8 + Filter: ((ft1.c3)::text = CASE WHEN (mod(ft1.c1, 4) = 0) THEN '_trig_update'::text ELSE '_update'::text COLLATE "C" END) + Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" +(4 rows) + +EXPLAIN (VERBOSE, COSTS OFF) +SELECT * FROM ft1 WHERE c3 = (CASE WHEN mod(c1, 4) = 0 THEN '_trig_update' COLLATE "C" ELSE '_update' END); + QUERY PLAN +---------------------------------------------------------------------------------------------------------------------------- + Foreign Scan on public.ft1 + Output: c1, c2, c3, c4, c5, c6, c7, c8 + Filter: ((ft1.c3)::text = CASE WHEN (mod(ft1.c1, 4) = 0) THEN '_trig_update'::text COLLATE "C" ELSE '_update'::text END) + Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" +(4 rows) + +EXPLAIN (VERBOSE, COSTS OFF) +SELECT * FROM ft1 WHERE c2 = (CASE WHEN mod(c1, 4) = 0 THEN 1 ELSE random() END); + QUERY PLAN +---------------------------------------------------------------------------------------------------------------------- + Foreign Scan on public.ft1 + Output: c1, c2, c3, c4, c5, c6, c7, c8 + Filter: ((ft1.c2)::double precision = CASE WHEN (mod(ft1.c1, 4) = 0) THEN '1'::double precision ELSE random() END) + Remote SQL: SELECT "C 1", c2, c3, c4, c5, c6, c7, c8 FROM "S 1"."T 1" +(4 rows) + -- Test UPDATE/DELETE with WHERE or JOIN/ON conditions containing -- user-defined operators/functions ALTER SERVER loopback OPTIONS (DROP extensions); diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index 02a6b15a13f..fb259a2f3af 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -1265,6 +1265,69 @@ UPDATE ft2 d SET c2 = CASE WHEN random() >= 0 THEN d.c2 ELSE 0 END UPDATE ft2 d SET c2 = CASE WHEN random() >= 0 THEN d.c2 ELSE 0 END FROM ft2 AS t WHERE d.c1 = t.c1 AND d.c1 > 1000; +-- Test CASE pushdown +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE ft2 d SET c2 = CASE WHEN c2 > 0 THEN c2 ELSE 0 END +WHERE c1 > 1000; + +UPDATE ft2 d SET c2 = CASE WHEN c2 > 0 THEN c2 ELSE 0 END +WHERE c1 > 1000; + +-- CASE in WHERE clause +EXPLAIN (VERBOSE, COSTS OFF) +SELECT c1,c2,c3 FROM ft2 WHERE CASE WHEN c2 > 600 THEN c2 END > 500 ORDER BY c1; + +SELECT c1,c2,c3 FROM ft2 WHERE CASE WHEN c2 > 600 THEN c2 END > 500 ORDER BY c1; + +-- Nested CASE +EXPLAIN (VERBOSE, COSTS OFF) +SELECT c1,c2,c3 FROM ft2 WHERE CASE CASE WHEN c2 > 0 THEN c2 END WHEN 100 THEN 601 WHEN c2 THEN c2 ELSE 0 END > 600 ORDER BY c1; + +SELECT c1,c2,c3 FROM ft2 WHERE CASE CASE WHEN c2 > 0 THEN c2 END WHEN 100 THEN 601 WHEN c2 THEN c2 ELSE 0 END > 600 ORDER BY c1; + +-- Aggregate function with CASE clause, both must be pushed down +EXPLAIN (VERBOSE, COSTS OFF) +SELECT sum(CASE WHEN mod(c1, 4) = 0 THEN 1 ELSE 2 END) FROM ft1; +-- Same but with out ELSE clause +EXPLAIN (VERBOSE, COSTS OFF) +SELECT sum(CASE WHEN mod(c1, 4) = 0 THEN 1 END) FROM ft1; +-- Different CASE form using a function in the condition +EXPLAIN (VERBOSE, COSTS OFF) +SELECT * FROM ft1 WHERE c1 > (CASE WHEN mod(c1, 4) = 0 THEN 1 ELSE 100 END); +EXPLAIN (VERBOSE, COSTS OFF) +SELECT * FROM ft1 WHERE c1 > (CASE mod(c1, 4) WHEN 0 THEN 1 WHEN 2 THEN 50 ELSE 100 END); +EXPLAIN (VERBOSE, COSTS OFF) +SELECT * FROM ft1 WHERE c1 > (CASE WHEN mod(c1, 4) = 0 THEN 1 WHEN mod(c1, 6) = 0 THEN 50 ELSE 100 END); +EXPLAIN (VERBOSE, COSTS OFF) +SELECT * FROM ft1 WHERE substr(c3, 6) = (CASE WHEN mod(c1, 4) = 0 THEN '_trig_update' ELSE '_update' END); +-- CASE involved in a prepared statement +PREPARE pre_case_select AS SELECT * FROM ft1 WHERE substr(c3, 6) = (CASE WHEN mod(c1, 4) = 0 THEN $1 ELSE $2 END); +EXPLAIN (VERBOSE, COSTS OFF) EXECUTE pre_case_select('_trig_update', '_update'); +DEALLOCATE pre_case_select; + +-- Test that CASE pushdown is not happening +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE ft2 d SET c2 = CASE WHEN random() >= 0 THEN c2 ELSE 0 END +WHERE c1 > 1000; + +UPDATE ft2 d SET c2 = CASE WHEN c2 > 0 THEN c2 ELSE 0 END +WHERE c1 > 1000; + +EXPLAIN (VERBOSE, COSTS OFF) +SELECT * FROM ft1 WHERE substr(c3, 6) COLLATE "C" = (CASE WHEN mod(c1, 4) = 0 THEN '_trig_update' COLLATE "C" ELSE '_update' COLLATE "C" END) COLLATE "C"; + +EXPLAIN (VERBOSE, COSTS OFF) +SELECT * FROM ft1 WHERE c3 = (CASE random() WHEN 0 THEN '_trig_update' ELSE '_update' END); + +EXPLAIN (VERBOSE, COSTS OFF) +SELECT * FROM ft1 WHERE c3 = (CASE WHEN mod(c1, 4) = 0 THEN '_trig_update' ELSE '_update' COLLATE "C" END); + +EXPLAIN (VERBOSE, COSTS OFF) +SELECT * FROM ft1 WHERE c3 = (CASE WHEN mod(c1, 4) = 0 THEN '_trig_update' COLLATE "C" ELSE '_update' END); + +EXPLAIN (VERBOSE, COSTS OFF) +SELECT * FROM ft1 WHERE c2 = (CASE WHEN mod(c1, 4) = 0 THEN 1 ELSE random() END); + -- Test UPDATE/DELETE with WHERE or JOIN/ON conditions containing -- user-defined operators/functions ALTER SERVER loopback OPTIONS (DROP extensions); -- 2.25.1