/*------------------------------------------------------------------------- * * deparse.c * Query deparser for postgres_fdw * * This file includes functions that examine query WHERE clauses to see * whether they're safe to send to the remote server for execution, as * well as functions to construct the query text to be sent. The latter * functionality is annoyingly duplicative of ruleutils.c, but there are * enough special considerations that it seems best to keep this separate. * One saving grace is that we only need deparse logic for node types that * we consider safe to send. * * We assume that the remote session's search_path is exactly "pg_catalog", * and thus we need schema-qualify all and only names outside pg_catalog. * * We do not consider that it is ever safe to send COLLATE expressions to * the remote server: it might not have the same collation names we do. * (Later we might consider it safe to send COLLATE "C", but even that would * fail on old remote servers.) An expression is considered safe to send only * if all collations used in it are traceable to Var(s) of the foreign table. * That implies that if the remote server gets a different answer than we do, * the foreign table's columns are not marked with collations that match the * remote table's columns, which we can consider to be user error. * * Portions Copyright (c) 2012-2013, PostgreSQL Global Development Group * * IDENTIFICATION * contrib/postgres_fdw/deparse.c * *------------------------------------------------------------------------- */ #include "postgres.h" #include "postgres_fdw.h" #include "access/htup.h" #include "access/sysattr.h" #include "access/transam.h" #include "catalog/pg_collation.h" #include "catalog/pg_namespace.h" #include "catalog/pg_operator.h" #include "catalog/pg_proc.h" #include "catalog/pg_type.h" #include "commands/defrem.h" #include "nodes/nodeFuncs.h" #include "optimizer/clauses.h" #include "optimizer/var.h" #include "parser/parsetree.h" #include "utils/builtins.h" #include "utils/lsyscache.h" #include "utils/syscache.h" /* * Global context for foreign_expr_walker's search of an expression tree. */ typedef struct foreign_glob_cxt { /* Input values */ PlannerInfo *root; RelOptInfo *foreignrel; /* Result values */ List *param_numbers; /* Param IDs of PARAM_EXTERN Params */ } foreign_glob_cxt; /* * Local (per-tree-level) context for foreign_expr_walker's search. * This is concerned with identifying collations used in the expression. */ typedef enum { FDW_COLLATE_NONE, /* expression is of a noncollatable type */ FDW_COLLATE_SAFE, /* collation derives from a foreign Var */ FDW_COLLATE_UNSAFE /* collation derives from something else */ } FDWCollateState; typedef struct foreign_loc_cxt { Oid collation; /* OID of current collation, if any */ FDWCollateState state; /* state of current collation choice */ } foreign_loc_cxt; /* * Functions to determine whether an expression can be evaluated safely on * remote server. */ static bool is_foreign_expr(PlannerInfo *root, RelOptInfo *baserel, Expr *expr, List **param_numbers); static bool foreign_expr_walker(Node *node, foreign_glob_cxt *glob_cxt, foreign_loc_cxt *outer_cxt); static bool is_builtin(Oid procid); /* * Functions to construct string representation of a node tree. */ static void deparseColumnRef(StringInfo buf, int varno, int varattno, PlannerInfo *root); static void deparseRelation(StringInfo buf, Oid relid); static void deparseStringLiteral(StringInfo buf, const char *val); static void deparseExpr(StringInfo buf, Expr *expr, PlannerInfo *root); static void deparseVar(StringInfo buf, Var *node, PlannerInfo *root); static void deparseConst(StringInfo buf, Const *node, PlannerInfo *root); static void deparseParam(StringInfo buf, Param *node, PlannerInfo *root); static void deparseArrayRef(StringInfo buf, ArrayRef *node, PlannerInfo *root); static void deparseFuncExpr(StringInfo buf, FuncExpr *node, PlannerInfo *root); static void deparseOpExpr(StringInfo buf, OpExpr *node, PlannerInfo *root); static void deparseOperatorName(StringInfo buf, Form_pg_operator opform); static void deparseDistinctExpr(StringInfo buf, DistinctExpr *node, PlannerInfo *root); static void deparseScalarArrayOpExpr(StringInfo buf, ScalarArrayOpExpr *node, PlannerInfo *root); static void deparseRelabelType(StringInfo buf, RelabelType *node, PlannerInfo *root); static void deparseBoolExpr(StringInfo buf, BoolExpr *node, PlannerInfo *root); static void deparseNullTest(StringInfo buf, NullTest *node, PlannerInfo *root); static void deparseArrayExpr(StringInfo buf, ArrayExpr *node, PlannerInfo *root); /* * Examine each restriction clause in baserel's baserestrictinfo list, * and classify them into three groups, which are returned as three lists: * - remote_conds contains expressions that can be evaluated remotely, * and contain no PARAM_EXTERN Params * - param_conds contains expressions that can be evaluated remotely, * but contain one or more PARAM_EXTERN Params * - local_conds contains all expressions that can't be evaluated remotely * * In addition, the fourth output parameter param_numbers receives an integer * list of the param IDs of the PARAM_EXTERN Params used in param_conds. * * The reason for segregating param_conds is mainly that it's difficult to * use such conditions in remote EXPLAIN. We could do it, but unless the * planner has been given representative values for all the Params, we'd * have to guess at representative values to use in EXPLAIN EXECUTE. * So for now we don't include them when doing remote EXPLAIN. */ void classifyConditions(PlannerInfo *root, RelOptInfo *baserel, List **remote_conds, List **param_conds, List **local_conds, List **param_numbers) { ListCell *lc; *remote_conds = NIL; *param_conds = NIL; *local_conds = NIL; *param_numbers = NIL; foreach(lc, baserel->baserestrictinfo) { RestrictInfo *ri = (RestrictInfo *) lfirst(lc); List *cur_param_numbers; if (is_foreign_expr(root, baserel, ri->clause, &cur_param_numbers)) { if (cur_param_numbers == NIL) *remote_conds = lappend(*remote_conds, ri); else { *param_conds = lappend(*param_conds, ri); /* Use list_concat_unique_int to get rid of duplicates */ *param_numbers = list_concat_unique_int(*param_numbers, cur_param_numbers); } } else *local_conds = lappend(*local_conds, ri); } } /* * Returns true if given expr is safe to evaluate on the foreign server. * * If result is true, we also return a list of param IDs of PARAM_EXTERN * Params appearing in the expr into *param_numbers. */ static bool is_foreign_expr(PlannerInfo *root, RelOptInfo *baserel, Expr *expr, List **param_numbers) { foreign_glob_cxt glob_cxt; foreign_loc_cxt loc_cxt; *param_numbers = NIL; /* default result */ /* * Check that the expression consists of nodes that are safe to execute * remotely. */ glob_cxt.root = root; glob_cxt.foreignrel = baserel; glob_cxt.param_numbers = NIL; loc_cxt.collation = InvalidOid; loc_cxt.state = FDW_COLLATE_NONE; if (!foreign_expr_walker((Node *) expr, &glob_cxt, &loc_cxt)) return false; /* Expressions examined here should be boolean, ie noncollatable */ Assert(loc_cxt.collation == InvalidOid); Assert(loc_cxt.state == FDW_COLLATE_NONE); /* * An expression which includes any mutable functions can't be sent over * because its result is not stable. For example, sending now() remote * side could cause confusion from clock offsets. Future versions might * be able to make this choice with more granularity. (We check this last * because it requires a lot of expensive catalog lookups.) */ if (contain_mutable_functions((Node *) expr)) return false; /* * OK, so return list of param IDs too. */ *param_numbers = glob_cxt.param_numbers; return true; } /* * Check if expression is safe to execute remotely, and return true if so. * * In addition, glob_cxt->param_numbers and *outer_cxt are updated. * * We must check that the expression contains only node types we can deparse, * that all types/functions/operators are safe to send (which we approximate * as being built-in), and that all collations used in the expression derive * from Vars of the foreign table. Because of the latter, the logic is * pretty close to assign_collations_walker() in parse_collate.c, though we * can assume here that the given expression is valid. */ static bool foreign_expr_walker(Node *node, foreign_glob_cxt *glob_cxt, foreign_loc_cxt *outer_cxt) { bool check_type = true; foreign_loc_cxt inner_cxt; Oid collation; FDWCollateState state; /* Need do nothing for empty subexpressions */ if (node == NULL) return true; /* Set up inner_cxt for possible recursion to child nodes */ inner_cxt.collation = InvalidOid; inner_cxt.state = FDW_COLLATE_NONE; switch (nodeTag(node)) { case T_Var: { Var *var = (Var *) node; /* * Var can be used if it is in the foreign table (we shouldn't * really see anything else in baserestrict clauses, but let's * check anyway). */ if (var->varno != glob_cxt->foreignrel->relid || var->varlevelsup != 0) return false; /* * If Var has a collation, consider that safe to use. */ collation = var->varcollid; state = OidIsValid(collation) ? FDW_COLLATE_SAFE : FDW_COLLATE_NONE; } break; case T_Const: { Const *c = (Const *) node; /* * If the constant has nondefault collation, either it's of a * non-builtin type, or it reflects folding of a CollateExpr; * either way, it's unsafe to send to the remote. */ if (c->constcollid != InvalidOid && c->constcollid != DEFAULT_COLLATION_OID) return false; /* Otherwise, we can consider that it doesn't set collation */ collation = InvalidOid; state = FDW_COLLATE_NONE; } break; case T_Param: { Param *p = (Param *) node; /* * Only external parameters can be sent to remote. (XXX This * needs to be improved, but at the point where this code * runs, we should only see PARAM_EXTERN Params anyway.) */ if (p->paramkind != PARAM_EXTERN) return false; /* * Collation handling is same as for Consts. */ if (p->paramcollid != InvalidOid && p->paramcollid != DEFAULT_COLLATION_OID) return false; collation = InvalidOid; state = FDW_COLLATE_NONE; /* * Report IDs of PARAM_EXTERN Params. We don't bother to * eliminate duplicate list elements here; classifyConditions * will do that. */ glob_cxt->param_numbers = lappend_int(glob_cxt->param_numbers, p->paramid); } break; case T_ArrayRef: { ArrayRef *ar = (ArrayRef *) node;; /* Assignment should not be in restrictions. */ if (ar->refassgnexpr != NULL) return false; /* * Recurse to remaining subexpressions. Since the array * subscripts must yield (noncollatable) integers, they won't * affect the inner_cxt state. */ if (!foreign_expr_walker((Node *) ar->refupperindexpr, glob_cxt, &inner_cxt)) return false; if (!foreign_expr_walker((Node *) ar->reflowerindexpr, glob_cxt, &inner_cxt)) return false; if (!foreign_expr_walker((Node *) ar->refexpr, glob_cxt, &inner_cxt)) return false; /* * Array subscripting should yield same collation as input, * but for safety use same logic as for function nodes. */ collation = ar->refcollid; if (collation == InvalidOid) state = FDW_COLLATE_NONE; else if (inner_cxt.state == FDW_COLLATE_SAFE && collation == inner_cxt.collation) state = FDW_COLLATE_SAFE; else state = FDW_COLLATE_UNSAFE; } break; case T_FuncExpr: { FuncExpr *fe = (FuncExpr *) node; /* * If function used by the expression is not built-in, it * can't be sent to remote because it might have incompatible * semantics on remote side. */ if (!is_builtin(fe->funcid)) return false; /* * Recurse to input subexpressions. */ if (!foreign_expr_walker((Node *) fe->args, glob_cxt, &inner_cxt)) return false; /* * If function's input collation is not derived from a foreign * Var, it can't be sent to remote. */ if (fe->inputcollid == InvalidOid) /* OK, inputs are all noncollatable */ ; else if (inner_cxt.state != FDW_COLLATE_SAFE || fe->inputcollid != inner_cxt.collation) return false; /* * Detect whether node is introducing a collation not derived * from a foreign Var. (If so, we just mark it unsafe for now * rather than immediately returning false, since the parent * node might not care.) */ collation = fe->funccollid; if (collation == InvalidOid) state = FDW_COLLATE_NONE; else if (inner_cxt.state == FDW_COLLATE_SAFE && collation == inner_cxt.collation) state = FDW_COLLATE_SAFE; else state = FDW_COLLATE_UNSAFE; } break; case T_OpExpr: case T_DistinctExpr: /* struct-equivalent to OpExpr */ { OpExpr *oe = (OpExpr *) node; /* * Similarly, only built-in operators can be sent to remote. * (If the operator is, surely its underlying function is * too.) */ if (!is_builtin(oe->opno)) return false; /* * Recurse to input subexpressions. */ if (!foreign_expr_walker((Node *) oe->args, glob_cxt, &inner_cxt)) return false; /* * If operator's input collation is not derived from a foreign * Var, it can't be sent to remote. */ if (oe->inputcollid == InvalidOid) /* OK, inputs are all noncollatable */ ; else if (inner_cxt.state != FDW_COLLATE_SAFE || oe->inputcollid != inner_cxt.collation) return false; /* Result-collation handling is same as for functions */ collation = oe->opcollid; if (collation == InvalidOid) state = FDW_COLLATE_NONE; else if (inner_cxt.state == FDW_COLLATE_SAFE && collation == inner_cxt.collation) state = FDW_COLLATE_SAFE; else state = FDW_COLLATE_UNSAFE; } break; case T_ScalarArrayOpExpr: { ScalarArrayOpExpr *oe = (ScalarArrayOpExpr *) node; /* * Again, only built-in operators can be sent to remote. */ if (!is_builtin(oe->opno)) return false; /* * Recurse to input subexpressions. */ if (!foreign_expr_walker((Node *) oe->args, glob_cxt, &inner_cxt)) return false; /* * If operator's input collation is not derived from a foreign * Var, it can't be sent to remote. */ if (oe->inputcollid == InvalidOid) /* OK, inputs are all noncollatable */ ; else if (inner_cxt.state != FDW_COLLATE_SAFE || oe->inputcollid != inner_cxt.collation) return false; /* Output is always boolean and so noncollatable. */ collation = InvalidOid; state = FDW_COLLATE_NONE; } break; case T_RelabelType: { RelabelType *r = (RelabelType *) node; /* * Recurse to input subexpression. */ if (!foreign_expr_walker((Node *) r->arg, glob_cxt, &inner_cxt)) return false; /* * RelabelType must not introduce a collation not derived from * an input foreign Var. */ collation = r->resultcollid; if (collation == InvalidOid) state = FDW_COLLATE_NONE; else if (inner_cxt.state == FDW_COLLATE_SAFE && collation == inner_cxt.collation) state = FDW_COLLATE_SAFE; else state = FDW_COLLATE_UNSAFE; } break; case T_BoolExpr: { BoolExpr *b = (BoolExpr *) node; /* * Recurse to input subexpressions. */ if (!foreign_expr_walker((Node *) b->args, glob_cxt, &inner_cxt)) return false; /* Output is always boolean and so noncollatable. */ collation = InvalidOid; state = FDW_COLLATE_NONE; } break; case T_NullTest: { NullTest *nt = (NullTest *) node; /* * Recurse to input subexpressions. */ if (!foreign_expr_walker((Node *) nt->arg, glob_cxt, &inner_cxt)) return false; /* Output is always boolean and so noncollatable. */ collation = InvalidOid; state = FDW_COLLATE_NONE; } break; case T_ArrayExpr: { ArrayExpr *a = (ArrayExpr *) node; /* * Recurse to input subexpressions. */ if (!foreign_expr_walker((Node *) a->elements, glob_cxt, &inner_cxt)) return false; /* * ArrayExpr must not introduce a collation not derived from * an input foreign Var. */ collation = a->array_collid; if (collation == InvalidOid) state = FDW_COLLATE_NONE; else if (inner_cxt.state == FDW_COLLATE_SAFE && collation == inner_cxt.collation) state = FDW_COLLATE_SAFE; else state = FDW_COLLATE_UNSAFE; } break; case T_List: { List *l = (List *) node; ListCell *lc; /* * Recurse to component subexpressions. */ foreach(lc, l) { if (!foreign_expr_walker((Node *) lfirst(lc), glob_cxt, &inner_cxt)) return false; } /* * When processing a list, collation state just bubbles up * from the list elements. */ collation = inner_cxt.collation; state = inner_cxt.state; /* Don't apply exprType() to the list. */ check_type = false; } break; default: /* * If it's anything else, assume it's unsafe. This list can be * expanded later, but don't forget to add deparse support below. */ return false; } /* * If result type of given expression is not built-in, it can't be sent to * remote because it might have incompatible semantics on remote side. */ if (check_type && !is_builtin(exprType(node))) return false; /* * Now, merge my collation information into my parent's state. */ if (state > outer_cxt->state) { /* Override previous parent state */ outer_cxt->collation = collation; outer_cxt->state = state; } else if (state == outer_cxt->state) { /* Merge, or detect error if there's a collation conflict */ switch (state) { case FDW_COLLATE_NONE: /* Nothing + nothing is still nothing */ break; case FDW_COLLATE_SAFE: if (collation != outer_cxt->collation) { /* * Non-default collation always beats default. */ if (outer_cxt->collation == DEFAULT_COLLATION_OID) { /* Override previous parent state */ outer_cxt->collation = collation; } else if (collation != DEFAULT_COLLATION_OID) { /* * Conflict; show state as indeterminate. We don't * want to "return false" right away, since parent * node might not care about collation. */ outer_cxt->state = FDW_COLLATE_UNSAFE; } } break; case FDW_COLLATE_UNSAFE: /* We're still conflicted ... */ break; } } /* It looks OK */ return true; } /* * Return true if given object is one of PostgreSQL's built-in objects. * * We use FirstBootstrapObjectId as the cutoff, so that we only consider * objects with hand-assigned OIDs to be "built in", not for instance any * function or type defined in the information_schema. * * Our constraints for dealing with types are tighter than they are for * functions or operators: we want to accept only types that are in pg_catalog, * else format_type might incorrectly fail to schema-qualify their names. * (This could be fixed with some changes to format_type, but for now there's * no need.) Thus we must exclude information_schema types. * * XXX there is a problem with this, which is that the set of built-in * objects expands over time. Something that is built-in to us might not * be known to the remote server, if it's of an older version. But keeping * track of that would be a huge exercise. */ static bool is_builtin(Oid oid) { return (oid < FirstBootstrapObjectId); } /* * Construct a simple SELECT statement that retrieves interesting columns * of the specified foreign table, and append it to "buf". The output * contains just "SELECT ... FROM tablename". * * "Interesting" columns are those appearing in the rel's targetlist or * in local_conds (conditions which can't be executed remotely). */ void deparseSimpleSql(StringInfo buf, PlannerInfo *root, RelOptInfo *baserel, List *local_conds) { RangeTblEntry *rte = root->simple_rte_array[baserel->relid]; Bitmapset *attrs_used = NULL; bool have_wholerow; bool first; AttrNumber attr; ListCell *lc; /* Collect all the attributes needed for joins or final output. */ pull_varattnos((Node *) baserel->reltargetlist, baserel->relid, &attrs_used); /* Add all the attributes used by local_conds. */ foreach(lc, local_conds) { RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc); pull_varattnos((Node *) rinfo->clause, baserel->relid, &attrs_used); } /* If there's a whole-row reference, we'll need all the columns. */ have_wholerow = bms_is_member(0 - FirstLowInvalidHeapAttributeNumber, attrs_used); /* * Construct SELECT list * * We list attributes in order of the foreign table's columns, but replace * any attributes that need not be fetched with NULL constants. (We can't * just omit such attributes, or we'll lose track of which columns are * which at runtime.) Note however that any dropped columns are ignored. */ appendStringInfo(buf, "SELECT "); first = true; for (attr = 1; attr <= baserel->max_attr; attr++) { /* Ignore dropped attributes. */ if (get_rte_attribute_is_dropped(rte, attr)) continue; if (!first) appendStringInfo(buf, ", "); first = false; if (have_wholerow || bms_is_member(attr - FirstLowInvalidHeapAttributeNumber, attrs_used)) deparseColumnRef(buf, baserel->relid, attr, root); else appendStringInfo(buf, "NULL"); } /* Don't generate bad syntax if no undropped columns */ if (first) appendStringInfo(buf, "NULL"); /* * Construct FROM clause */ appendStringInfo(buf, " FROM "); deparseRelation(buf, rte->relid); } /* * Deparse WHERE clauses in given list of RestrictInfos and append them to buf. * * If no WHERE clause already exists in the buffer, is_first should be true. */ void appendWhereClause(StringInfo buf, bool is_first, List *exprs, PlannerInfo *root) { int nestlevel; ListCell *lc; /* Make sure any constants in the exprs are printed portably */ nestlevel = set_transmission_modes(); foreach(lc, exprs) { RestrictInfo *ri = (RestrictInfo *) lfirst(lc); /* Connect expressions with "AND" and parenthesize each condition. */ if (is_first) appendStringInfo(buf, " WHERE "); else appendStringInfo(buf, " AND "); appendStringInfoChar(buf, '('); deparseExpr(buf, ri->clause, root); appendStringInfoChar(buf, ')'); is_first = false; } reset_transmission_modes(nestlevel); } /* * Construct SELECT statement to acquire size in blocks of given relation. * * Note: we use local definition of block size, not remote definition. * This is perhaps debatable. * * Note: pg_relation_size() exists in 8.1 and later. */ void deparseAnalyzeSizeSql(StringInfo buf, Relation rel) { Oid relid = RelationGetRelid(rel); StringInfoData relname; /* We'll need the remote relation name as a literal. */ initStringInfo(&relname); deparseRelation(&relname, relid); appendStringInfo(buf, "SELECT pg_catalog.pg_relation_size("); deparseStringLiteral(buf, relname.data); appendStringInfo(buf, "::pg_catalog.regclass) / %d", BLCKSZ); } /* * Construct SELECT statement to acquire sample rows of given relation. * * Note: command is appended to whatever might be in buf already. */ void deparseAnalyzeSql(StringInfo buf, Relation rel) { Oid relid = RelationGetRelid(rel); TupleDesc tupdesc = RelationGetDescr(rel); int i; char *colname; List *options; ListCell *lc; bool first = true; appendStringInfo(buf, "SELECT "); for (i = 0; i < tupdesc->natts; i++) { /* Ignore dropped columns. */ if (tupdesc->attrs[i]->attisdropped) continue; /* Use attribute name or column_name option. */ colname = NameStr(tupdesc->attrs[i]->attname); options = GetForeignColumnOptions(relid, i + 1); foreach(lc, options) { DefElem *def = (DefElem *) lfirst(lc); if (strcmp(def->defname, "column_name") == 0) { colname = defGetString(def); break; } } if (!first) appendStringInfo(buf, ", "); appendStringInfoString(buf, quote_identifier(colname)); first = false; } /* Don't generate bad syntax for zero-column relation. */ if (first) appendStringInfo(buf, "NULL"); /* * Construct FROM clause */ appendStringInfo(buf, " FROM "); deparseRelation(buf, relid); } /* * Construct name to use for given column, and emit it into buf. * If it has a column_name FDW option, use that instead of attribute name. */ static void deparseColumnRef(StringInfo buf, int varno, int varattno, PlannerInfo *root) { RangeTblEntry *rte; char *colname = NULL; List *options; ListCell *lc; /* varno must not be any of OUTER_VAR, INNER_VAR and INDEX_VAR. */ Assert(varno >= 1 && varno <= root->simple_rel_array_size); /* Get RangeTblEntry from array in PlannerInfo. */ rte = root->simple_rte_array[varno]; /* * If it's a column of a foreign table, and it has the column_name FDW * option, use that value. */ options = GetForeignColumnOptions(rte->relid, varattno); foreach(lc, options) { DefElem *def = (DefElem *) lfirst(lc); if (strcmp(def->defname, "column_name") == 0) { colname = defGetString(def); break; } } /* * If it's a column of a regular table or it doesn't have column_name FDW * option, use attribute name. */ if (colname == NULL) colname = get_relid_attribute_name(rte->relid, varattno); appendStringInfoString(buf, quote_identifier(colname)); } /* * Append remote name of specified foreign table to buf. * Use value of table_name FDW option (if any) instead of relation's name. * Similarly, schema_name FDW option overrides schema name. */ static void deparseRelation(StringInfo buf, Oid relid) { ForeignTable *table; const char *nspname = NULL; const char *relname = NULL; ListCell *lc; /* obtain additional catalog information. */ table = GetForeignTable(relid); /* * Use value of FDW options if any, instead of the name of object itself. */ foreach(lc, table->options) { DefElem *def = (DefElem *) lfirst(lc); if (strcmp(def->defname, "schema_name") == 0) nspname = defGetString(def); else if (strcmp(def->defname, "table_name") == 0) relname = defGetString(def); } /* * Note: we could skip printing the schema name if it's pg_catalog, * but that doesn't seem worth the trouble. */ if (nspname == NULL) nspname = get_namespace_name(get_rel_namespace(relid)); if (relname == NULL) relname = get_rel_name(relid); appendStringInfo(buf, "%s.%s", quote_identifier(nspname), quote_identifier(relname)); } /* * Append a SQL string literal representing "val" to buf. */ static void deparseStringLiteral(StringInfo buf, const char *val) { const char *valptr; /* * Rather than making assumptions about the remote server's value of * standard_conforming_strings, always use E'foo' syntax if there are any * backslashes. This will fail on remote servers before 8.1, but those * are long out of support. */ if (strchr(val, '\\') != NULL) appendStringInfoChar(buf, ESCAPE_STRING_SYNTAX); appendStringInfoChar(buf, '\''); for (valptr = val; *valptr; valptr++) { char ch = *valptr; if (SQL_STR_DOUBLE(ch, true)) appendStringInfoChar(buf, ch); appendStringInfoChar(buf, ch); } appendStringInfoChar(buf, '\''); } /* * Deparse given expression into buf. * * This function must support all the same node types that foreign_expr_walker * accepts. * * Note: unlike ruleutils.c, we just use a simple hard-wired parenthesization * scheme: anything more complex than a Var, Const, function call or cast * should be self-parenthesized. */ static void deparseExpr(StringInfo buf, Expr *node, PlannerInfo *root) { if (node == NULL) return; switch (nodeTag(node)) { case T_Var: deparseVar(buf, (Var *) node, root); break; case T_Const: deparseConst(buf, (Const *) node, root); break; case T_Param: deparseParam(buf, (Param *) node, root); break; case T_ArrayRef: deparseArrayRef(buf, (ArrayRef *) node, root); break; case T_FuncExpr: deparseFuncExpr(buf, (FuncExpr *) node, root); break; case T_OpExpr: deparseOpExpr(buf, (OpExpr *) node, root); break; case T_DistinctExpr: deparseDistinctExpr(buf, (DistinctExpr *) node, root); break; case T_ScalarArrayOpExpr: deparseScalarArrayOpExpr(buf, (ScalarArrayOpExpr *) node, root); break; case T_RelabelType: deparseRelabelType(buf, (RelabelType *) node, root); break; case T_BoolExpr: deparseBoolExpr(buf, (BoolExpr *) node, root); break; case T_NullTest: deparseNullTest(buf, (NullTest *) node, root); break; case T_ArrayExpr: deparseArrayExpr(buf, (ArrayExpr *) node, root); break; default: elog(ERROR, "unsupported expression type for deparse: %d", (int) nodeTag(node)); break; } } /* * Deparse given Var node into buf. */ static void deparseVar(StringInfo buf, Var *node, PlannerInfo *root) { Assert(node->varlevelsup == 0); deparseColumnRef(buf, node->varno, node->varattno, root); } /* * Deparse given constant value into buf. * * This function has to be kept in sync with ruleutils.c's get_const_expr. */ static void deparseConst(StringInfo buf, Const *node, PlannerInfo *root) { Oid typoutput; bool typIsVarlena; char *extval; bool isfloat = false; bool needlabel; if (node->constisnull) { appendStringInfo(buf, "NULL"); appendStringInfo(buf, "::%s", format_type_with_typemod(node->consttype, node->consttypmod)); return; } getTypeOutputInfo(node->consttype, &typoutput, &typIsVarlena); extval = OidOutputFunctionCall(typoutput, node->constvalue); switch (node->consttype) { case INT2OID: case INT4OID: case INT8OID: case OIDOID: case FLOAT4OID: case FLOAT8OID: case NUMERICOID: { /* * No need to quote unless it's a special value such as 'NaN'. * See comments in get_const_expr(). */ if (strspn(extval, "0123456789+-eE.") == strlen(extval)) { if (extval[0] == '+' || extval[0] == '-') appendStringInfo(buf, "(%s)", extval); else appendStringInfoString(buf, extval); if (strcspn(extval, "eE.") != strlen(extval)) isfloat = true; /* it looks like a float */ } else appendStringInfo(buf, "'%s'", extval); } break; case BITOID: case VARBITOID: appendStringInfo(buf, "B'%s'", extval); break; case BOOLOID: if (strcmp(extval, "t") == 0) appendStringInfoString(buf, "true"); else appendStringInfoString(buf, "false"); break; default: deparseStringLiteral(buf, extval); break; } /* * Append ::typename unless the constant will be implicitly typed as the * right type when it is read in. * * XXX this code has to be kept in sync with the behavior of the parser, * especially make_const. */ switch (node->consttype) { case BOOLOID: case INT4OID: case UNKNOWNOID: needlabel = false; break; case NUMERICOID: needlabel = !isfloat || (node->consttypmod >= 0); break; default: needlabel = true; break; } if (needlabel) appendStringInfo(buf, "::%s", format_type_with_typemod(node->consttype, node->consttypmod)); } /* * Deparse given Param node into buf. * * We don't need to renumber the parameter ID, because the executor functions * in postgres_fdw.c preserve the numbering of PARAM_EXTERN Params. * (This might change soon.) * * Note: we label the Param's type explicitly rather than relying on * transmitting a numeric type OID in PQexecParams(). This allows us to * avoid assuming that types have the same OIDs on the remote side as they * do locally --- they need only have the same names. */ static void deparseParam(StringInfo buf, Param *node, PlannerInfo *root) { Assert(node->paramkind == PARAM_EXTERN); appendStringInfo(buf, "$%d", node->paramid); appendStringInfo(buf, "::%s", format_type_with_typemod(node->paramtype, node->paramtypmod)); } /* * Deparse an array subscript expression. */ static void deparseArrayRef(StringInfo buf, ArrayRef *node, PlannerInfo *root) { ListCell *lowlist_item; ListCell *uplist_item; /* Always parenthesize the expression. */ appendStringInfoChar(buf, '('); /* * Deparse referenced array expression first. If that expression includes * a cast, we have to parenthesize to prevent the array subscript from * being taken as typename decoration. We can avoid that in the typical * case of subscripting a Var, but otherwise do it. */ if (IsA(node->refexpr, Var)) deparseExpr(buf, node->refexpr, root); else { appendStringInfoChar(buf, '('); deparseExpr(buf, node->refexpr, root); appendStringInfoChar(buf, ')'); } /* Deparse subscript expressions. */ lowlist_item = list_head(node->reflowerindexpr); /* could be NULL */ foreach(uplist_item, node->refupperindexpr) { appendStringInfoChar(buf, '['); if (lowlist_item) { deparseExpr(buf, lfirst(lowlist_item), root); appendStringInfoChar(buf, ':'); lowlist_item = lnext(lowlist_item); } deparseExpr(buf, lfirst(uplist_item), root); appendStringInfoChar(buf, ']'); } appendStringInfoChar(buf, ')'); } /* * Deparse given node which represents a function call into buf. */ static void deparseFuncExpr(StringInfo buf, FuncExpr *node, PlannerInfo *root) { HeapTuple proctup; Form_pg_proc procform; const char *proname; bool first; ListCell *arg; /* * If the function call came from an implicit coercion, then just show the * first argument. */ if (node->funcformat == COERCE_IMPLICIT_CAST) { deparseExpr(buf, (Expr *) linitial(node->args), root); return; } /* * If the function call came from a cast, then show the first argument * plus an explicit cast operation. */ if (node->funcformat == COERCE_EXPLICIT_CAST) { Oid rettype = node->funcresulttype; int32 coercedTypmod; /* Get the typmod if this is a length-coercion function */ (void) exprIsLengthCoercion((Node *) node, &coercedTypmod); deparseExpr(buf, (Expr *) linitial(node->args), root); appendStringInfo(buf, "::%s", format_type_with_typemod(rettype, coercedTypmod)); return; } /* * Normal function: display as proname(args). */ proctup = SearchSysCache1(PROCOID, ObjectIdGetDatum(node->funcid)); if (!HeapTupleIsValid(proctup)) elog(ERROR, "cache lookup failed for function %u", node->funcid); procform = (Form_pg_proc) GETSTRUCT(proctup); /* Print schema name only if it's not pg_catalog */ if (procform->pronamespace != PG_CATALOG_NAMESPACE) { const char *schemaname; schemaname = get_namespace_name(procform->pronamespace); appendStringInfo(buf, "%s.", quote_identifier(schemaname)); } /* Deparse the function name ... */ proname = NameStr(procform->proname); appendStringInfo(buf, "%s(", quote_identifier(proname)); /* ... and all the arguments */ first = true; foreach(arg, node->args) { if (!first) appendStringInfoString(buf, ", "); deparseExpr(buf, (Expr *) lfirst(arg), root); first = false; } appendStringInfoChar(buf, ')'); ReleaseSysCache(proctup); } /* * Deparse given operator expression into buf. To avoid problems around * priority of operations, we always parenthesize the arguments. */ static void deparseOpExpr(StringInfo buf, OpExpr *node, PlannerInfo *root) { HeapTuple tuple; Form_pg_operator form; char oprkind; ListCell *arg; /* Retrieve information about the operator from system catalog. */ tuple = SearchSysCache1(OPEROID, ObjectIdGetDatum(node->opno)); if (!HeapTupleIsValid(tuple)) elog(ERROR, "cache lookup failed for operator %u", node->opno); form = (Form_pg_operator) GETSTRUCT(tuple); oprkind = form->oprkind; /* Sanity check. */ Assert((oprkind == 'r' && list_length(node->args) == 1) || (oprkind == 'l' && list_length(node->args) == 1) || (oprkind == 'b' && list_length(node->args) == 2)); /* Always parenthesize the expression. */ appendStringInfoChar(buf, '('); /* Deparse left operand. */ if (oprkind == 'r' || oprkind == 'b') { arg = list_head(node->args); deparseExpr(buf, lfirst(arg), root); appendStringInfoChar(buf, ' '); } /* Deparse operator name. */ deparseOperatorName(buf, form); /* Deparse right operand. */ if (oprkind == 'l' || oprkind == 'b') { arg = list_tail(node->args); appendStringInfoChar(buf, ' '); deparseExpr(buf, lfirst(arg), root); } appendStringInfoChar(buf, ')'); ReleaseSysCache(tuple); } /* * Print the name of an operator. */ static void deparseOperatorName(StringInfo buf, Form_pg_operator opform) { char *opname; /* opname is not a SQL identifier, so we should not quote it. */ opname = NameStr(opform->oprname); /* Print schema name only if it's not pg_catalog */ if (opform->oprnamespace != PG_CATALOG_NAMESPACE) { const char *opnspname; opnspname = get_namespace_name(opform->oprnamespace); /* Print fully qualified operator name. */ appendStringInfo(buf, "OPERATOR(%s.%s)", quote_identifier(opnspname), opname); } else { /* Just print operator name. */ appendStringInfo(buf, "%s", opname); } } /* * Deparse IS DISTINCT FROM. */ static void deparseDistinctExpr(StringInfo buf, DistinctExpr *node, PlannerInfo *root) { Assert(list_length(node->args) == 2); appendStringInfoChar(buf, '('); deparseExpr(buf, linitial(node->args), root); appendStringInfo(buf, " IS DISTINCT FROM "); deparseExpr(buf, lsecond(node->args), root); appendStringInfoChar(buf, ')'); } /* * Deparse given ScalarArrayOpExpr expression into buf. To avoid problems * around priority of operations, we always parenthesize the arguments. */ static void deparseScalarArrayOpExpr(StringInfo buf, ScalarArrayOpExpr *node, PlannerInfo *root) { HeapTuple tuple; Form_pg_operator form; Expr *arg1; Expr *arg2; /* Retrieve information about the operator from system catalog. */ tuple = SearchSysCache1(OPEROID, ObjectIdGetDatum(node->opno)); if (!HeapTupleIsValid(tuple)) elog(ERROR, "cache lookup failed for operator %u", node->opno); form = (Form_pg_operator) GETSTRUCT(tuple); /* Sanity check. */ Assert(list_length(node->args) == 2); /* Always parenthesize the expression. */ appendStringInfoChar(buf, '('); /* Deparse left operand. */ arg1 = linitial(node->args); deparseExpr(buf, arg1, root); appendStringInfoChar(buf, ' '); /* Deparse operator name plus decoration. */ deparseOperatorName(buf, form); appendStringInfo(buf, " %s (", node->useOr ? "ANY" : "ALL"); /* Deparse right operand. */ arg2 = lsecond(node->args); deparseExpr(buf, arg2, root); appendStringInfoChar(buf, ')'); /* Always parenthesize the expression. */ appendStringInfoChar(buf, ')'); ReleaseSysCache(tuple); } /* * Deparse a RelabelType (binary-compatible cast) node. */ static void deparseRelabelType(StringInfo buf, RelabelType *node, PlannerInfo *root) { deparseExpr(buf, node->arg, root); if (node->relabelformat != COERCE_IMPLICIT_CAST) appendStringInfo(buf, "::%s", format_type_with_typemod(node->resulttype, node->resulttypmod)); } /* * Deparse a BoolExpr node. * * Note: by the time we get here, AND and OR expressions have been flattened * into N-argument form, so we'd better be prepared to deal with that. */ static void deparseBoolExpr(StringInfo buf, BoolExpr *node, PlannerInfo *root) { const char *op = NULL; /* keep compiler quiet */ bool first; ListCell *lc; switch (node->boolop) { case AND_EXPR: op = "AND"; break; case OR_EXPR: op = "OR"; break; case NOT_EXPR: appendStringInfo(buf, "(NOT "); deparseExpr(buf, linitial(node->args), root); appendStringInfoChar(buf, ')'); return; } appendStringInfoChar(buf, '('); first = true; foreach(lc, node->args) { if (!first) appendStringInfo(buf, " %s ", op); deparseExpr(buf, (Expr *) lfirst(lc), root); first = false; } appendStringInfoChar(buf, ')'); } /* * Deparse IS [NOT] NULL expression. */ static void deparseNullTest(StringInfo buf, NullTest *node, PlannerInfo *root) { appendStringInfoChar(buf, '('); deparseExpr(buf, node->arg, root); if (node->nulltesttype == IS_NULL) appendStringInfo(buf, " IS NULL)"); else appendStringInfo(buf, " IS NOT NULL)"); } /* * Deparse ARRAY[...] construct. */ static void deparseArrayExpr(StringInfo buf, ArrayExpr *node, PlannerInfo *root) { bool first = true; ListCell *lc; appendStringInfo(buf, "ARRAY["); foreach(lc, node->elements) { if (!first) appendStringInfo(buf, ", "); deparseExpr(buf, lfirst(lc), root); first = false; } appendStringInfoChar(buf, ']'); /* If the array is empty, we need an explicit cast to the array type. */ if (node->elements == NIL) appendStringInfo(buf, "::%s", format_type_with_typemod(node->array_typeid, -1)); }