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Diffstat (limited to 'contrib/postgres_fdw/deparse.c')
| -rw-r--r-- | contrib/postgres_fdw/deparse.c | 1104 |
1 files changed, 1104 insertions, 0 deletions
diff --git a/contrib/postgres_fdw/deparse.c b/contrib/postgres_fdw/deparse.c new file mode 100644 index 00000000000..7fc1f797ab2 --- /dev/null +++ b/contrib/postgres_fdw/deparse.c @@ -0,0 +1,1104 @@ +/*------------------------------------------------------------------------- + * + * 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. + * + * 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_details.h" +#include "access/sysattr.h" +#include "access/transam.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" + + +/* + * Context for foreign_expr_walker's search of an expression tree. + */ +typedef struct foreign_expr_cxt +{ + /* Input values */ + PlannerInfo *root; + RelOptInfo *foreignrel; + /* Result values */ + List *param_numbers; /* Param IDs of PARAM_EXTERN Params */ +} foreign_expr_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_expr_cxt *context); +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 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_expr_cxt context; + + *param_numbers = NIL; /* default result */ + + /* + * Check that the expression consists of nodes that are safe to execute + * remotely. + */ + context.root = root; + context.foreignrel = baserel; + context.param_numbers = NIL; + if (foreign_expr_walker((Node *) expr, &context)) + return false; + + /* + * 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 = context.param_numbers; + + return true; +} + +/* + * Return true if expression includes any node that is not safe to execute + * remotely. (We use this convention because expression_tree_walker is + * designed to abort the tree walk as soon as a TRUE result is detected.) + */ +static bool +foreign_expr_walker(Node *node, foreign_expr_cxt *context) +{ + bool check_type = true; + + if (node == NULL) + return false; + + switch (nodeTag(node)) + { + case T_Var: + { + /* + * 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). + */ + Var *var = (Var *) node; + + if (var->varno != context->foreignrel->relid || + var->varlevelsup != 0) + return true; + } + break; + case T_Const: + /* OK */ + 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 true; + + /* + * Report IDs of PARAM_EXTERN Params. We don't bother to + * eliminate duplicate list elements here; classifyConditions + * will do that. + */ + context->param_numbers = lappend_int(context->param_numbers, + p->paramid); + } + break; + case T_ArrayRef: + { + ArrayRef *ar = (ArrayRef *) node;; + + /* Assignment should not be in restrictions. */ + if (ar->refassgnexpr != NULL) + return true; + } + break; + case T_FuncExpr: + { + /* + * 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. + */ + FuncExpr *fe = (FuncExpr *) node; + + if (!is_builtin(fe->funcid)) + return true; + } + break; + case T_OpExpr: + case T_DistinctExpr: /* struct-equivalent to OpExpr */ + { + /* + * Similarly, only built-in operators can be sent to remote. + * (If the operator is, surely its underlying function is + * too.) + */ + OpExpr *oe = (OpExpr *) node; + + if (!is_builtin(oe->opno)) + return true; + } + break; + case T_ScalarArrayOpExpr: + { + /* + * Again, only built-in operators can be sent to remote. + */ + ScalarArrayOpExpr *oe = (ScalarArrayOpExpr *) node; + + if (!is_builtin(oe->opno)) + return true; + } + break; + case T_RelabelType: + case T_BoolExpr: + case T_NullTest: + case T_ArrayExpr: + /* OK */ + break; + case T_List: + + /* + * We need only fall through to let expression_tree_walker scan + * the list elements --- but 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 true; + } + + /* + * 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 true; + + /* Recurse to examine sub-nodes */ + return expression_tree_walker(node, foreign_expr_walker, context); +} + +/* + * Return true if given object is one of PostgreSQL's built-in objects. + * + * 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 < FirstNormalObjectId); +} + + +/* + * 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 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); + } + + /* + * 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 (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) +{ + ListCell *lc; + + 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; + } +} + +/* + * 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); + } + + 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.) + */ +static void +deparseParam(StringInfo buf, Param *node, PlannerInfo *root) +{ + Assert(node->paramkind == PARAM_EXTERN); + appendStringInfo(buf, "$%d", node->paramid); +} + +/* + * 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. + * + * Here not only explicit function calls and explicit casts but also implicit + * casts are deparsed to avoid problems caused by different cast settings + * between local and remote. + * + * Function name is always qualified by schema name to avoid problems caused + * by different setting of search_path on remote side. + */ +static void +deparseFuncExpr(StringInfo buf, FuncExpr *node, PlannerInfo *root) +{ + HeapTuple proctup; + Form_pg_proc procform; + const char *proname; + const char *schemaname; + bool use_variadic; + bool first; + ListCell *arg; + + 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); + proname = NameStr(procform->proname); + + /* Check if need to print VARIADIC (cf. ruleutils.c) */ + if (OidIsValid(procform->provariadic)) + { + if (procform->provariadic != ANYOID) + use_variadic = true; + else + use_variadic = node->funcvariadic; + } + else + use_variadic = false; + + /* Deparse the function name ... */ + schemaname = get_namespace_name(procform->pronamespace); + appendStringInfo(buf, "%s.%s(", + quote_identifier(schemaname), + quote_identifier(proname)); + /* ... and all the arguments */ + first = true; + foreach(arg, node->args) + { + if (!first) + appendStringInfoString(buf, ", "); + if (use_variadic && lnext(arg) == NULL) + appendStringInfoString(buf, "VARIADIC "); + 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. Also we use + * OPERATOR(schema.operator) notation to determine remote operator exactly. + */ +static void +deparseOpExpr(StringInfo buf, OpExpr *node, PlannerInfo *root) +{ + HeapTuple tuple; + Form_pg_operator form; + const char *opnspname; + char *opname; + 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); + + opnspname = quote_identifier(get_namespace_name(form->oprnamespace)); + /* opname is not a SQL identifier, so we don't need to quote it. */ + opname = NameStr(form->oprname); + 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 fully qualified operator name. */ + appendStringInfo(buf, "OPERATOR(%s.%s)", opnspname, opname); + + /* Deparse right operand. */ + if (oprkind == 'l' || oprkind == 'b') + { + arg = list_tail(node->args); + appendStringInfoChar(buf, ' '); + deparseExpr(buf, lfirst(arg), root); + } + + appendStringInfoChar(buf, ')'); + + ReleaseSysCache(tuple); +} + +/* + * 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. Also + * we use OPERATOR(schema.operator) notation to determine remote operator + * exactly. + */ +static void +deparseScalarArrayOpExpr(StringInfo buf, + ScalarArrayOpExpr *node, + PlannerInfo *root) +{ + HeapTuple tuple; + Form_pg_operator form; + const char *opnspname; + char *opname; + 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); + + opnspname = quote_identifier(get_namespace_name(form->oprnamespace)); + /* opname is not a SQL identifier, so we don't need to quote it. */ + opname = NameStr(form->oprname); + + /* 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); + + /* Deparse fully qualified operator name plus decoration. */ + appendStringInfo(buf, " OPERATOR(%s.%s) %s (", + opnspname, opname, 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); + 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)); +} |