/*------------------------------------------------------------------------- * * deparse.c * Foreign-data wrapper for remote MySQL servers * * Portions Copyright (c) 2012-2014, PostgreSQL Global Development Group * * Portions Copyright (c) 2004-2014, EnterpriseDB Corporation. * * IDENTIFICATION * deparse.c * *------------------------------------------------------------------------- */ #include "postgres.h" #include "mysql_fdw.h" #include "access/heapam.h" #include "access/htup_details.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" static char *mysql_quote_identifier(const char *s, char q); /* * Global context for foreign_expr_walker's search of an expression tree. */ typedef struct foreign_glob_cxt { PlannerInfo *root; /* global planner state */ RelOptInfo *foreignrel; /* the foreign relation we are planning for */ } 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; /* * Context for deparseExpr */ typedef struct deparse_expr_cxt { PlannerInfo *root; /* global planner state */ RelOptInfo *foreignrel; /* the foreign relation we are planning for */ StringInfo buf; /* output buffer to append to */ List **params_list; /* exprs that will become remote Params */ } deparse_expr_cxt; /* * Functions to construct string representation of a node tree. */ static void deparseExpr(Expr *expr, deparse_expr_cxt *context); static void mysql_deparse_var(Var *node, deparse_expr_cxt *context); static void mysql_deparse_const(Const *node, deparse_expr_cxt *context); static void mysql_deparse_param(Param *node, deparse_expr_cxt *context); static void mysql_deparse_array_ref(ArrayRef *node, deparse_expr_cxt *context); static void mysql_deparse_func_expr(FuncExpr *node, deparse_expr_cxt *context); static void mysql_deparse_op_expr(OpExpr *node, deparse_expr_cxt *context); static void mysql_deparse_operator_name(StringInfo buf, Form_pg_operator opform); static void mysql_deparse_distinct_expr(DistinctExpr *node, deparse_expr_cxt *context); static void mysql_deparse_scalar_array_op_expr(ScalarArrayOpExpr *node, deparse_expr_cxt *context); static void mysql_deparse_relabel_type(RelabelType *node, deparse_expr_cxt *context); static void mysql_deparse_bool_expr(BoolExpr *node, deparse_expr_cxt *context); static void mysql_deparse_null_test(NullTest *node, deparse_expr_cxt *context); static void mysql_deparse_array_expr(ArrayExpr *node, deparse_expr_cxt *context); static void mysql_print_remote_param(int paramindex, Oid paramtype, int32 paramtypmod, deparse_expr_cxt *context); static void mysql_print_remote_placeholder(Oid paramtype, int32 paramtypmod, deparse_expr_cxt *context); static void mysql_deparse_relation(StringInfo buf, Relation rel); static void mysql_deparse_target_list(StringInfo buf, PlannerInfo *root, Index rtindex, Relation rel, Bitmapset *attrs_used, List **retrieved_attrs); static void mysql_deparse_column_ref(StringInfo buf, int varno, int varattno, PlannerInfo *root); /* * 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 mysql_deparse_relation(StringInfo buf, Relation rel) { ForeignTable *table; const char *nspname = NULL; const char *relname = NULL; ListCell *lc = NULL; /* obtain additional catalog information. */ table = GetForeignTable(RelationGetRelid(rel)); /* * 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, "dbname") == 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(RelationGetNamespace(rel)); if (relname == NULL) relname = RelationGetRelationName(rel); appendStringInfo(buf, "%s.%s", mysql_quote_identifier(nspname, '`'), mysql_quote_identifier(relname, '`')); } static char * mysql_quote_identifier(const char *s , char q) { char *result = palloc(strlen(s) * 2 + 3); char *r = result; *r++ = q; while (*s) { if (*s == q) *r++ = *s; *r++ = *s; s++; } *r++ = q; *r++ = '\0'; return result; } /* * Deparese SELECT statment */ void mysql_deparse_select(StringInfo buf, PlannerInfo *root, RelOptInfo *baserel, Bitmapset *attrs_used, char *svr_table, List **retrieved_attrs) { RangeTblEntry *rte = planner_rt_fetch(baserel->relid, root); Relation rel; /* * Core code already has some lock on each rel being planned, so we can * use NoLock here. */ rel = heap_open(rte->relid, NoLock); appendStringInfoString(buf, "SELECT "); mysql_deparse_target_list(buf, root, baserel->relid, rel, attrs_used, retrieved_attrs); /* * Construct FROM clause */ appendStringInfoString(buf, " FROM "); mysql_deparse_relation(buf, rel); heap_close(rel, NoLock); } /* * deparse remote INSERT statement * * The statement text is appended to buf, and we also create an integer List * of the columns being retrieved by RETURNING (if any), which is returned * to *retrieved_attrs. */ void mysql_deparse_insert(StringInfo buf, PlannerInfo *root, Index rtindex, Relation rel, List *targetAttrs) { AttrNumber pindex; bool first; ListCell *lc; appendStringInfoString(buf, "INSERT INTO "); mysql_deparse_relation(buf, rel); if (targetAttrs) { appendStringInfoChar(buf, '('); first = true; foreach(lc, targetAttrs) { int attnum = lfirst_int(lc); if (!first) appendStringInfoString(buf, ", "); first = false; mysql_deparse_column_ref(buf, rtindex, attnum, root); } appendStringInfoString(buf, ") VALUES ("); pindex = 1; first = true; foreach(lc, targetAttrs) { if (!first) appendStringInfoString(buf, ", "); first = false; appendStringInfo(buf, "?"); pindex++; } appendStringInfoChar(buf, ')'); } else appendStringInfoString(buf, " DEFAULT VALUES"); } void mysql_deparse_analyze(StringInfo sql, char *dbname, char *relname) { appendStringInfo(sql, "SELECT"); appendStringInfo(sql, " round(((data_length + index_length)), 2)"); appendStringInfo(sql, " FROM information_schema.TABLES"); appendStringInfo(sql, " WHERE table_schema = '%s' AND table_name = '%s'", dbname, relname); } /* * Emit a target list that retrieves the columns specified in attrs_used. * This is used for both SELECT and RETURNING targetlists. */ static void mysql_deparse_target_list(StringInfo buf, PlannerInfo *root, Index rtindex, Relation rel, Bitmapset *attrs_used, List **retrieved_attrs) { TupleDesc tupdesc = RelationGetDescr(rel); bool have_wholerow; bool first; int i; /* If there's a whole-row reference, we'll need all the columns. */ have_wholerow = bms_is_member(0 - FirstLowInvalidHeapAttributeNumber, attrs_used); first = true; *retrieved_attrs = NIL; for (i = 1; i <= tupdesc->natts; i++) { Form_pg_attribute attr = tupdesc->attrs[i - 1]; /* Ignore dropped attributes. */ if (attr->attisdropped) continue; if (have_wholerow || bms_is_member(i - FirstLowInvalidHeapAttributeNumber, attrs_used)) { if (!first) appendStringInfoString(buf, ", "); first = false; mysql_deparse_column_ref(buf, rtindex, i, root); *retrieved_attrs = lappend_int(*retrieved_attrs, i); } } /* Don't generate bad syntax if no undropped columns */ if (first) appendStringInfoString(buf, "NULL"); } /* * Deparse WHERE clauses in given list of RestrictInfos and append them to buf. * * baserel is the foreign table we're planning for. * * If no WHERE clause already exists in the buffer, is_first should be true. * * If params is not NULL, it receives a list of Params and other-relation Vars * used in the clauses; these values must be transmitted to the remote server * as parameter values. * * If params is NULL, we're generating the query for EXPLAIN purposes, * so Params and other-relation Vars should be replaced by dummy values. */ void mysql_append_where_clause(StringInfo buf, PlannerInfo *root, RelOptInfo *baserel, List *exprs, bool is_first, List **params) { deparse_expr_cxt context; ListCell *lc; if (params) *params = NIL; /* initialize result list to empty */ /* Set up context struct for recursion */ context.root = root; context.foreignrel = baserel; context.buf = buf; context.params_list = params; foreach(lc, exprs) { RestrictInfo *ri = (RestrictInfo *) lfirst(lc); /* Connect expressions with "AND" and parenthesize each condition. */ if (is_first) appendStringInfoString(buf, " WHERE "); else appendStringInfoString(buf, " AND "); appendStringInfoChar(buf, '('); deparseExpr(ri->clause, &context); appendStringInfoChar(buf, ')'); is_first = false; } } /* * 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 mysql_deparse_column_ref(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(!IS_SPECIAL_VARNO(varno)); /* Get RangeTblEntry from array in PlannerInfo. */ rte = planner_rt_fetch(varno, root); /* * 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, mysql_quote_identifier(colname, '`')); } static void mysql_deparse_string(StringInfo buf, const char *val, bool isstr) { const char *valptr; int i = -1; for (valptr = val; *valptr; valptr++) { char ch = *valptr; i++; if (i == 0 && isstr) appendStringInfoChar(buf, '\''); /* * Remove '{', '}' and \" character from the string. Because * this syntax is not recognize by the remote MySQL server. */ if ((ch == '{' && i == 0) || (ch == '}' && (i == (strlen(val) - 1))) || ch == '\"') continue; if (ch == ',' && isstr) { appendStringInfoChar(buf, '\''); appendStringInfoChar(buf, ch); appendStringInfoChar(buf, ' '); appendStringInfoChar(buf, '\''); continue; } appendStringInfoChar(buf, ch); } if (isstr) appendStringInfoChar(buf, '\''); } /* * Append a SQL string literal representing "val" to buf. */ static void mysql_deparse_string_literal(StringInfo buf, const char *val) { const char *valptr; 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 context->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(Expr *node, deparse_expr_cxt *context) { if (node == NULL) return; switch (nodeTag(node)) { case T_Var: mysql_deparse_var((Var *) node, context); break; case T_Const: mysql_deparse_const((Const *) node, context); break; case T_Param: mysql_deparse_param((Param *) node, context); break; case T_ArrayRef: mysql_deparse_array_ref((ArrayRef *) node, context); break; case T_FuncExpr: mysql_deparse_func_expr((FuncExpr *) node, context); break; case T_OpExpr: mysql_deparse_op_expr((OpExpr *) node, context); break; case T_DistinctExpr: mysql_deparse_distinct_expr((DistinctExpr *) node, context); break; case T_ScalarArrayOpExpr: mysql_deparse_scalar_array_op_expr((ScalarArrayOpExpr *) node, context); break; case T_RelabelType: mysql_deparse_relabel_type((RelabelType *) node, context); break; case T_BoolExpr: mysql_deparse_bool_expr((BoolExpr *) node, context); break; case T_NullTest: mysql_deparse_null_test((NullTest *) node, context); break; case T_ArrayExpr: mysql_deparse_array_expr((ArrayExpr *) node, context); break; default: elog(ERROR, "unsupported expression type for deparse: %d", (int) nodeTag(node)); break; } } /* * deparse remote UPDATE statement * * The statement text is appended to buf, and we also create an integer List * of the columns being retrieved by RETURNING (if any), which is returned * to *retrieved_attrs. */ void mysql_deparse_update(StringInfo buf, PlannerInfo *root, Index rtindex, Relation rel, List *targetAttrs, char *attname) { AttrNumber pindex; bool first; ListCell *lc; appendStringInfoString(buf, "UPDATE "); mysql_deparse_relation(buf, rel); appendStringInfoString(buf, " SET "); pindex = 2; first = true; foreach(lc, targetAttrs) { int attnum = lfirst_int(lc); if (attnum == 1) continue; if (!first) appendStringInfoString(buf, ", "); first = false; mysql_deparse_column_ref(buf, rtindex, attnum, root); appendStringInfo(buf, " = ?"); pindex++; } appendStringInfo(buf, " WHERE %s = ?", attname); } /* * deparse remote DELETE statement * * The statement text is appended to buf, and we also create an integer List * of the columns being retrieved by RETURNING (if any), which is returned * to *retrieved_attrs. */ void mysql_deparse_delete(StringInfo buf, PlannerInfo *root, Index rtindex, Relation rel, char *name) { appendStringInfoString(buf, "DELETE FROM "); mysql_deparse_relation(buf, rel); appendStringInfo(buf, " WHERE %s = ?", name); } /* * Deparse given Var node into context->buf. * * If the Var belongs to the foreign relation, just print its remote name. * Otherwise, it's effectively a Param (and will in fact be a Param at * run time). Handle it the same way we handle plain Params --- see * deparseParam for comments. */ static void mysql_deparse_var(Var *node, deparse_expr_cxt *context) { StringInfo buf = context->buf; if (node->varno == context->foreignrel->relid && node->varlevelsup == 0) { /* Var belongs to foreign table */ mysql_deparse_column_ref(buf, node->varno, node->varattno, context->root); } else { /* Treat like a Param */ if (context->params_list) { int pindex = 0; ListCell *lc; /* find its index in params_list */ foreach(lc, *context->params_list) { pindex++; if (equal(node, (Node *) lfirst(lc))) break; } if (lc == NULL) { /* not in list, so add it */ pindex++; *context->params_list = lappend(*context->params_list, node); } mysql_print_remote_param(pindex, node->vartype, node->vartypmod, context); } else { mysql_print_remote_placeholder(node->vartype, node->vartypmod, context); } } } /* * Deparse given constant value into context->buf. * * This function has to be kept in sync with ruleutils.c's get_const_expr. */ static void mysql_deparse_const(Const *node, deparse_expr_cxt *context) { StringInfo buf = context->buf; Oid typoutput; bool typIsVarlena; char *extval; if (node->constisnull) { appendStringInfoString(buf, "NULL"); 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); } 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: mysql_deparse_string_literal(buf, extval); break; } } /* * Deparse given Param node. * * If we're generating the query "for real", add the Param to * context->params_list if it's not already present, and then use its index * in that list as the remote parameter number. During EXPLAIN, there's * no need to identify a parameter number. */ static void mysql_deparse_param(Param *node, deparse_expr_cxt *context) { if (context->params_list) { int pindex = 0; ListCell *lc; /* find its index in params_list */ foreach(lc, *context->params_list) { pindex++; if (equal(node, (Node *) lfirst(lc))) break; } if (lc == NULL) { /* not in list, so add it */ pindex++; *context->params_list = lappend(*context->params_list, node); } mysql_print_remote_param(pindex, node->paramtype, node->paramtypmod, context); } else { mysql_print_remote_placeholder(node->paramtype, node->paramtypmod, context); } } /* * Deparse an array subscript expression. */ static void mysql_deparse_array_ref(ArrayRef *node, deparse_expr_cxt *context) { StringInfo buf = context->buf; 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(node->refexpr, context); else { appendStringInfoChar(buf, '('); deparseExpr(node->refexpr, context); 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(lfirst(lowlist_item), context); appendStringInfoChar(buf, ':'); lowlist_item = lnext(lowlist_item); } deparseExpr(lfirst(uplist_item), context); appendStringInfoChar(buf, ']'); } appendStringInfoChar(buf, ')'); } /* * This possible that name of function in PostgreSQL and * mysql differ, so return the mysql equelent function name */ static char* mysql_replace_function(char *in) { if (strcmp(in, "btrim") == 0) { return "trim"; } return in; } /* * Deparse a function call. */ static void mysql_deparse_func_expr(FuncExpr *node, deparse_expr_cxt *context) { StringInfo buf = context->buf; HeapTuple proctup; Form_pg_proc procform; const char *proname; bool first; ListCell *arg; /* * 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); /* Translate PostgreSQL function into mysql function */ proname = mysql_replace_function(NameStr(procform->proname)); /* Deparse the function name ... */ appendStringInfo(buf, "%s(", proname); /* ... and all the arguments */ first = true; foreach(arg, node->args) { if (!first) appendStringInfoString(buf, ", "); deparseExpr((Expr *) lfirst(arg), context); first = false; } appendStringInfoChar(buf, ')'); ReleaseSysCache(proctup); } /* * Deparse given operator expression. To avoid problems around * priority of operations, we always parenthesize the arguments. */ static void mysql_deparse_op_expr(OpExpr *node, deparse_expr_cxt *context) { StringInfo buf = context->buf; 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(lfirst(arg), context); appendStringInfoChar(buf, ' '); } /* Deparse operator name. */ mysql_deparse_operator_name(buf, form); /* Deparse right operand. */ if (oprkind == 'l' || oprkind == 'b') { arg = list_tail(node->args); appendStringInfoChar(buf, ' '); deparseExpr(lfirst(arg), context); } appendStringInfoChar(buf, ')'); ReleaseSysCache(tuple); } /* * Print the name of an operator. */ static void mysql_deparse_operator_name(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)", mysql_quote_identifier(opnspname, '`'), opname); } else { if (strcmp(opname, "~~") == 0) { appendStringInfoString(buf, "LIKE BINARY"); } else if (strcmp(opname, "~~*") == 0) { appendStringInfoString(buf, "LIKE"); } else if (strcmp(opname, "!~~") == 0) { appendStringInfoString(buf, "NOT LIKE BINARY"); } else if (strcmp(opname, "!~~*") == 0) { appendStringInfoString(buf, "NOT LIKE"); } else if (strcmp(opname, "~") == 0) { appendStringInfoString(buf, "REGEXP BINARY"); } else if (strcmp(opname, "~*") == 0) { appendStringInfoString(buf, "REGEXP"); } else if (strcmp(opname, "!~") == 0) { appendStringInfoString(buf, "NOT REGEXP BINARY"); } else if (strcmp(opname, "!~*") == 0) { appendStringInfoString(buf, "NOT REGEXP"); } else { appendStringInfoString(buf, opname); } } } /* * Deparse IS DISTINCT FROM. */ static void mysql_deparse_distinct_expr(DistinctExpr *node, deparse_expr_cxt *context) { StringInfo buf = context->buf; Assert(list_length(node->args) == 2); appendStringInfoChar(buf, '('); deparseExpr(linitial(node->args), context); appendStringInfoString(buf, " IS DISTINCT FROM "); deparseExpr(lsecond(node->args), context); appendStringInfoChar(buf, ')'); } /* * Deparse given ScalarArrayOpExpr expression. To avoid problems * around priority of operations, we always parenthesize the arguments. */ static void mysql_deparse_scalar_array_op_expr(ScalarArrayOpExpr *node, deparse_expr_cxt *context) { StringInfo buf = context->buf; HeapTuple tuple; Expr *arg1; Expr *arg2; Form_pg_operator form; char *opname; Oid typoutput; bool typIsVarlena; char *extval; /* 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); /* Deparse left operand. */ arg1 = linitial(node->args); deparseExpr(arg1, context); appendStringInfoChar(buf, ' '); opname = NameStr(form->oprname); if (strcmp(opname, "<>") == 0) appendStringInfo(buf, " NOT "); /* Deparse operator name plus decoration. */ appendStringInfo(buf, " IN ("); /* Deparse right operand. */ arg2 = lsecond(node->args); switch (nodeTag((Node*)arg2)) { case T_Const: { Const *c = (Const*)arg2; if (!c->constisnull) { getTypeOutputInfo(c->consttype, &typoutput, &typIsVarlena); extval = OidOutputFunctionCall(typoutput, c->constvalue); switch (c->consttype) { case INT4ARRAYOID: case OIDARRAYOID: mysql_deparse_string(buf, extval, false); break; default: mysql_deparse_string(buf, extval, true); break; } } else { appendStringInfoString(buf, " NULL"); return; } } break; default: deparseExpr(arg2, context); break; } appendStringInfoChar(buf, ')'); ReleaseSysCache(tuple); } /* * Deparse a RelabelType (binary-compatible cast) node. */ static void mysql_deparse_relabel_type(RelabelType *node, deparse_expr_cxt *context) { deparseExpr(node->arg, context); } /* * 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 mysql_deparse_bool_expr(BoolExpr *node, deparse_expr_cxt *context) { StringInfo buf = context->buf; 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: appendStringInfoString(buf, "(NOT "); deparseExpr(linitial(node->args), context); appendStringInfoChar(buf, ')'); return; } appendStringInfoChar(buf, '('); first = true; foreach(lc, node->args) { if (!first) appendStringInfo(buf, " %s ", op); deparseExpr((Expr *) lfirst(lc), context); first = false; } appendStringInfoChar(buf, ')'); } /* * Deparse IS [NOT] NULL expression. */ static void mysql_deparse_null_test(NullTest *node, deparse_expr_cxt *context) { StringInfo buf = context->buf; appendStringInfoChar(buf, '('); deparseExpr(node->arg, context); if (node->nulltesttype == IS_NULL) appendStringInfoString(buf, " IS NULL)"); else appendStringInfoString(buf, " IS NOT NULL)"); } /* * Deparse ARRAY[...] construct. */ static void mysql_deparse_array_expr(ArrayExpr *node, deparse_expr_cxt *context) { StringInfo buf = context->buf; bool first = true; ListCell *lc; appendStringInfoString(buf, "ARRAY["); foreach(lc, node->elements) { if (!first) appendStringInfoString(buf, ", "); deparseExpr(lfirst(lc), context); first = false; } appendStringInfoChar(buf, ']'); } /* * Print the representation of a parameter to be sent to the remote side. * * Note: we always 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 mysql_print_remote_param(int paramindex, Oid paramtype, int32 paramtypmod, deparse_expr_cxt *context) { StringInfo buf = context->buf; appendStringInfo(buf, "?"); } static void mysql_print_remote_placeholder(Oid paramtype, int32 paramtypmod, deparse_expr_cxt *context) { StringInfo buf = context->buf; appendStringInfo(buf, "(SELECT null)"); } /* * 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); } /* * Check if expression is safe to execute remotely, and return true if so. * * In addition, *outer_cxt is updated with collation information. * * 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; /* * If the Var is from the foreign table, we consider its * collation (if any) safe to use. If it is from another * table, we treat its collation the same way as we would a * Param's collation, ie it's not safe for it to have a * non-default collation. */ if (var->varno == glob_cxt->foreignrel->relid && var->varlevelsup == 0) { /* Var belongs to foreign table */ collation = var->varcollid; state = OidIsValid(collation) ? FDW_COLLATE_SAFE : FDW_COLLATE_NONE; } else { /* Var belongs to some other table */ if (var->varcollid != InvalidOid && var->varcollid != DEFAULT_COLLATION_OID) return false; /* We can consider that it doesn't set collation */ collation = InvalidOid; state = 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: { /* We are not supporting param push down*/ return false; } 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; } /* * Returns true if given expr is safe to evaluate on the foreign server. */ bool is_foreign_expr(PlannerInfo *root, RelOptInfo *baserel, Expr *expr) { foreign_glob_cxt glob_cxt; foreign_loc_cxt loc_cxt; /* * Check that the expression consists of nodes that are safe to execute * remotely. */ glob_cxt.root = root; glob_cxt.foreignrel = baserel; 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); /* OK to evaluate on the remote server */ return true; }