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deparse.c
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/*-------------------------------------------------------------------------
*
* deparse.c
* Query deparser for odbc_fdw
*
* Portions Copyright (c) 2021, TOSHIBA CORPORATION
* Portions Copyright (c) 2012-2021, PostgreSQL Global Development Group
*
* IDENTIFICATION
* contrib/odbc_fdw/deparse.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/htup_details.h"
#include "access/sysattr.h"
#include "access/table.h"
#include "catalog/pg_aggregate.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 "common/keywords.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "nodes/plannodes.h"
#include "optimizer/optimizer.h"
#include "optimizer/prep.h"
#include "optimizer/tlist.h"
#include "parser/parsetree.h"
#include "odbc_fdw.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
#include "utils/syscache.h"
#include "utils/typcache.h"
#include "commands/tablecmds.h"
#include "catalog/namespace.h"
#include "catalog/pg_type.h"
/*
* Global context for odbc_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 */
Relids relids; /* relids of base relations in the underlying
* scan */
} foreign_glob_cxt;
/*
* Local (per-tree-level) context for odbc_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, or
* it has default collation that is not
* traceable to a foreign Var */
FDW_COLLATE_SAFE, /* collation derives from a foreign Var */
FDW_COLLATE_UNSAFE /* collation is non-default and derives from
* something other than a foreign Var */
} FDWCollateState;
typedef struct foreign_loc_cxt
{
Oid collation; /* OID of current collation, if any */
FDWCollateState state; /* state of current collation choice */
bool is_op_args; /* outer is T_OpExpr or not */
bool is_scalar_array_op_arg; /* outer is T_ScalarArrayOpExpr or not */
} foreign_loc_cxt;
/*
* odbcSupportedBuiltinAggFunction
* List of supported builtin aggregate functions for odbc
*/
static const char *odbcSupportedBuiltinAggFunction[] = {
"avg",
"bit_and",
"bit_or",
"count",
"max",
"min",
"stddev_pop",
"stddev_samp",
"sum",
"var_pop",
"var_samp",
NULL};
/*
* odbcSupportedBuiltinOperators
* List of supported builtin operator for odbc
*/
static const char *odbcSupportedBuiltinOperators[] = {
/* Comparison operators */
">",
"<",
">=",
"<=",
"=",
"<>",
"!=",
/* Mathematical operators */
"+",
"-",
"*",
/* "/", Does not support / operator */
"%", /* MOD */
/* String operators */
"||", /* Concatenates */
/* Pattern matching operators */
"~~", /* LIKE */
"!~~", /* NOT LIKE */
NULL};
/*
* OdbcCommonFunctions:
* - List of common function for ODBC driver
* - This list is confirmed with PostgreSQL and MySQL.
*/
static const char *OdbcCommonFunctions[] = {
"nullif",
/* Numeric functions */
"abs",
"acos",
"asin",
"atan",
"atan2",
"ceil",
"ceiling",
"cos",
"cot",
"degrees",
"div",
"exp",
"floor",
"ln",
"log",
"log10",
"mod",
"pow",
"power",
"radians",
"round",
"sign",
"sin",
"sqrt",
"tan",
/* String functions */
"ascii",
"bit_length",
"char_length",
"character_length",
"concat",
"concat_ws",
"left",
"length",
"lower",
"lpad",
"octet_length",
"repeat",
"replace",
"reverse",
"right",
"rpad",
"position",
"regexp_replace",
"substr",
"substring",
"upper",
/* Datetime function */
"date",
NULL};
/*
* CastFunctions
* List of PostgreSQL cast functions, these functions can be push down.
*/
static const char *CastFunctions[] = {
"float4",
/* date time cast */
"date",
"time",
NULL};
bool odbc_is_builtin(Oid oid);
static bool odbc_foreign_expr_walker(Node *node,
foreign_glob_cxt *glob_cxt,
foreign_loc_cxt *outer_cxt);
/*
* Functions to construct string representation of a node tree.
*/
static void odbc_deparse_target_list(StringInfo buf,
RangeTblEntry *rte,
Index rtindex,
Relation rel,
bool is_returning,
Bitmapset *attrs_used,
bool qualify_col,
List **retrieved_attrs,
deparse_expr_cxt *context);
static void odbc_deparse_expr(Expr *expr, deparse_expr_cxt *context);
static void odbc_deparse_var(Var *node, deparse_expr_cxt *context);
static void odbc_deparse_const(Const *node, deparse_expr_cxt *context);
static void odbc_deparse_op_expr(OpExpr *node, deparse_expr_cxt *context);
static void odbc_deparse_nullif_expr(NullIfExpr *node, deparse_expr_cxt *context);
static void odbc_deparse_operator_name(StringInfo buf, Form_pg_operator opform);
static void odbc_deparse_bool_expr(BoolExpr *node, deparse_expr_cxt *context);
static void odbc_deparse_null_test(NullTest *node, deparse_expr_cxt *context);
static void odbc_deparse_boolean_test(BooleanTest *node, deparse_expr_cxt *context);
static void odbc_deparse_aggref(Aggref *node, deparse_expr_cxt *context);
static void odbc_deparse_func_expr(FuncExpr *node, deparse_expr_cxt *context);
static char *odbc_deparse_cast_function(char *function_name, Oid type_oid, int32 typemod);
static void odbc_deparse_select_sql(List *tlist, List **retrieved_attrs,
deparse_expr_cxt *context);
static void odbc_deparse_from_expr_for_rel(StringInfo buf, PlannerInfo *root,
RelOptInfo *foreignrel, bool use_alias,
Index ignore_rel, List **ignore_conds,
List **params_list);
static void odbc_deparse_from_expr(List *quals, deparse_expr_cxt *context);
static void odbc_deparse_string_literal(StringInfo buf, const char *val);
static void odbc_deparse_function_name(Oid funcid, deparse_expr_cxt *context);
static void odbc_deparse_explicit_target_list(List *tlist,
bool is_returning,
List **retrieved_attrs,
deparse_expr_cxt *context);
static void odbc_deparse_scalar_array_op_expr(ScalarArrayOpExpr *node, deparse_expr_cxt *context);
static bool odbc_is_str_exist_in_list(char *str, const char **list);
static void odbc_deconstruct_constant_array(Const *node, bool **elem_nulls,
Datum **elem_values, Oid *elmtype, int *num_elems);
static void odbc_append_constant_value(StringInfo buf, Oid const_type, char *extval);
static void odbc_append_conditions(List *exprs, deparse_expr_cxt *context);
static bool odbc_is_supported_type(Oid type);
static bool odbc_is_supported_builtin_func(Oid funcid, char *in);
/*
* Returns true if given expr is safe to evaluate on the foreign server.
*/
bool
odbc_is_foreign_expr(PlannerInfo *root,
RelOptInfo *baserel,
Expr *expr)
{
foreign_glob_cxt glob_cxt;
foreign_loc_cxt loc_cxt;
OdbcFdwRelationInfo *fpinfo = (OdbcFdwRelationInfo *) (baserel->fdw_private);
/*
* Check that the expression consists of nodes that are safe to execute
* remotely.
*/
glob_cxt.root = root;
glob_cxt.foreignrel = baserel;
/*
* For an upper relation, use relids from its underneath scan relation,
* because the upperrel's own relids currently aren't set to anything
* meaningful by the core code. For other relation, use their own relids.
*/
if (IS_UPPER_REL(baserel))
glob_cxt.relids = fpinfo->outerrel->relids;
else
glob_cxt.relids = baserel->relids;
loc_cxt.collation = InvalidOid;
loc_cxt.state = FDW_COLLATE_NONE;
loc_cxt.is_op_args = false;
loc_cxt.is_scalar_array_op_arg = false;
if (!odbc_foreign_expr_walker((Node *) expr, &glob_cxt, &loc_cxt))
return false;
/*
* If the expression has a valid collation that does not arise from a
* foreign var, the expression can not be sent over.
*/
if (loc_cxt.state == FDW_COLLATE_UNSAFE)
return false;
/* OK to evaluate on the remote server */
return true;
}
/*
* 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 (they are "shippable"),
* 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. Note function mutability is not
* currently considered here.
*/
static bool
odbc_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;
HeapTuple tuple;
/* 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;
inner_cxt.is_op_args = outer_cxt->is_op_args;
inner_cxt.is_scalar_array_op_arg = outer_cxt->is_scalar_array_op_arg;
switch (nodeTag(node))
{
case T_Var:
{
Var *var = (Var *) node;
/* Check var type if it is an arg of an operator */
if (outer_cxt->is_op_args && !odbc_is_supported_type(var->vartype))
return false;
/*
* 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 (bms_is_member(var->varno, glob_cxt->relids) &&
var->varlevelsup == 0)
{
/* Var belongs to foreign table */
/*
* System columns should not be sent to the remote, since
* we don't make any effort to ensure that local and
* remote values match (tableoid, in particular, almost
* certainly doesn't match).
*/
if (var->varattno < 0)
return false;
/* Else check the collation */
collation = var->varcollid;
state = OidIsValid(collation) ? FDW_COLLATE_SAFE : FDW_COLLATE_NONE;
}
else
{
/* Parameter is unsupported */
return false;
}
}
break;
case T_Const:
{
Const *c = (Const *) node;
/* Does not support push-down bytea constant */
if (c->consttype == BYTEAOID)
return false;
/* Check const type if it is an arg of an operator */
if (outer_cxt->is_op_args && !odbc_is_supported_type(c->consttype))
return false;
/*
* If the constant has nondefault collation, either it's of a
* non-builtin type, or it reflects folding of a CollateExpr.
* It's unsafe to send to the remote unless it's used in a
* non-collation-sensitive context.
*/
collation = c->constcollid;
if (collation == InvalidOid ||
collation == DEFAULT_COLLATION_OID)
state = FDW_COLLATE_NONE;
else
state = FDW_COLLATE_UNSAFE;
}
break;
case T_DistinctExpr:
/* Does not support pushdown T_DistinctExpr */
return false;
case T_NullIfExpr:
case T_OpExpr:
{
OpExpr *oe = (OpExpr *) node;
char *oprname;
Form_pg_operator form;
/*
* Similarly, only built-in operators can be sent to remote.
* (If the operator is, surely its underlying function is
* too.)
*/
if (!odbc_is_builtin(oe->opno))
return false;
tuple = SearchSysCache1(OPEROID, ObjectIdGetDatum(oe->opno));
if (!HeapTupleIsValid(tuple))
elog(ERROR, "cache lookup failed for operator %u", oe->opno);
form = (Form_pg_operator) GETSTRUCT(tuple);
/* Get operation name */
oprname = pstrdup(NameStr(form->oprname));
ReleaseSysCache(tuple);
/*
* odbc does not support push-down operator which not exsisted
* in odbcSupportedBuiltinOperators
*/
if (!odbc_is_str_exist_in_list(oprname, odbcSupportedBuiltinOperators))
return false;
/*
* Recurse to input subexpressions.
*/
inner_cxt.is_op_args = true;
if (!odbc_foreign_expr_walker((Node *) oe->args,
glob_cxt, &inner_cxt))
return false;
inner_cxt.is_op_args = 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 if (collation == DEFAULT_COLLATION_OID)
state = FDW_COLLATE_NONE;
else
state = FDW_COLLATE_UNSAFE;
}
break;
case T_BoolExpr:
{
BoolExpr *b = (BoolExpr *) node;
/*
* Recurse to input subexpressions.
*/
if (!odbc_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 (!odbc_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_BooleanTest:
{
BooleanTest *bt = (BooleanTest *) node;
if (bt->booltesttype == IS_UNKNOWN || bt->booltesttype == IS_NOT_UNKNOWN)
return false;
/*
* Recurse to input subexpressions.
*/
if (!odbc_foreign_expr_walker((Node *) bt->arg,
glob_cxt, &inner_cxt))
return false;
/* Output is always boolean and so noncollatable. */
collation = InvalidOid;
state = FDW_COLLATE_NONE;
}
break;
case T_ScalarArrayOpExpr:
{
ScalarArrayOpExpr *oe = (ScalarArrayOpExpr *) node;
Form_pg_operator form;
char *oprname = NULL;
/*
* Again, only built-in operators can be sent to remote.
*/
if (!odbc_is_builtin(oe->opno))
return false;
tuple = SearchSysCache1(OPEROID, ObjectIdGetDatum(oe->opno));
if (!HeapTupleIsValid(tuple))
elog(ERROR, "cache lookup failed for operator %u", oe->opno);
form = (Form_pg_operator) GETSTRUCT(tuple);
/* Get operation name */
oprname = pstrdup(NameStr(form->oprname));
ReleaseSysCache(tuple);
/* Only support push down equal or not-equal operator. */
if (!(strcmp(oprname, "=") == 0 ||
strcmp(oprname, "<>") == 0 ||
strcmp(oprname, "!=") == 0))
return false;
/*
* Recurse to input subexpressions.
*/
inner_cxt.is_scalar_array_op_arg = true;
if (!odbc_foreign_expr_walker((Node *) oe->args,
glob_cxt, &inner_cxt))
return false;
inner_cxt.is_scalar_array_op_arg = 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_ArrayExpr:
{
ArrayExpr *a = (ArrayExpr *) node;
/* just support array in side T_ScalarArrayOpExpr */
if (!inner_cxt.is_scalar_array_op_arg)
return false;
/*
* Recurse to input subexpressions.
*/
if (!odbc_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 (!odbc_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;
case T_Aggref:
{
Aggref *agg = (Aggref *) node;
ListCell *lc;
char *aggname = NULL;
/* Not safe to pushdown when not in grouping context */
if (!IS_UPPER_REL(glob_cxt->foreignrel))
return false;
/* Only non-split aggregates are pushable. */
if (agg->aggsplit != AGGSPLIT_SIMPLE)
return false;
/*
* Does not support VARIADIC, FILTER and ORDER BY inside
* aggregate function
*/
if (agg->aggfilter != NULL ||
agg->aggorder != NIL ||
agg->aggvariadic == true)
return false;
/* get function name */
aggname = get_func_name(agg->aggfnoid);
/*
* Does not push down aggregate function if it not in
* odbcSupportedBuiltinAggFunction
*/
if (!odbc_is_str_exist_in_list(aggname, odbcSupportedBuiltinAggFunction))
return false;
if (agg->aggdistinct != NIL &&
!(strcmp(aggname, "max") == 0 ||
strcmp(aggname, "min") == 0 ||
strcmp(aggname, "avg") == 0 ||
strcmp(aggname, "sum") == 0 ||
strcmp(aggname, "count") == 0))
return false;
/*
* Recurse to input args.
*/
foreach(lc, agg->args)
{
Node *n = (Node *) lfirst(lc);
/* If TargetEntry, extract the expression from it */
if (IsA(n, TargetEntry))
{
TargetEntry *tle = (TargetEntry *) n;
n = (Node *) tle->expr;
}
if (!odbc_foreign_expr_walker(n, glob_cxt, &inner_cxt))
return false;
}
/*
* If aggregate's input collation is not derived from a
* foreign Var, it can't be sent to remote.
*/
if (agg->inputcollid == InvalidOid)
/* OK, inputs are all noncollatable */ ;
else if (inner_cxt.state != FDW_COLLATE_SAFE ||
agg->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 = agg->aggcollid;
if (collation == InvalidOid)
state = FDW_COLLATE_NONE;
else if (inner_cxt.state == FDW_COLLATE_SAFE &&
collation == inner_cxt.collation)
state = FDW_COLLATE_SAFE;
else if (collation == DEFAULT_COLLATION_OID)
state = FDW_COLLATE_NONE;
else
state = FDW_COLLATE_UNSAFE;
}
break;
case T_FuncExpr:
{
FuncExpr *fe = (FuncExpr *) node;
char *funcname = NULL;
bool is_cast_functions = false;
bool is_common_function = false;
/*
* 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.
*/
funcname = get_func_name(fe->funcid);
/* check NULL for funcname */
if (funcname == NULL)
elog(ERROR, "cache lookup failed for function %u", fe->funcid);
/*
* Check cast functions:
* - IMPLICIT CAST will be skip
* - EXPLICIT CAST existed in CastFunctions list will be pushed-down
*/
if (fe->funcformat == COERCE_IMPLICIT_CAST ||
(fe->funcformat == COERCE_EXPLICIT_CAST &&
odbc_is_str_exist_in_list(funcname, CastFunctions)))
{
is_cast_functions = true;
}
else if (fe->funcformat != COERCE_EXPLICIT_CAST)
{
/* odbc supported builtin functions */
if (odbc_is_supported_builtin_func(fe->funcid, funcname))
is_common_function = true;
}
/*
* Does not push down function to odbc data source if it not
* a supported cast function or common function
*/
if (!is_cast_functions &&
!is_common_function)
return false;
/* Just support push-down log with 2 arguments */
if (strcmp(funcname, "log") == 0 && list_length(fe->args) != 2)
return false;
/* Does not support push-down regexp_replace with more than 3 arguments */
if (strcmp(funcname, "regexp_replace") == 0 && list_length(fe->args) > 3)
return false;
/*
* Recurse to input subexpressions.
*/
if (!odbc_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;
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 shippable, it can't be sent
* to remote because it might have incompatible semantics on remote side.
*/
if (check_type && !odbc_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;
}
/*
* Examine each qual clause in input_conds, and classify them into two groups,
* which are returned as two lists:
* - remote_conds contains expressions that can be evaluated remotely
* - local_conds contains expressions that can't be evaluated remotely
*/
void
odbc_classify_conditions(PlannerInfo *root,
RelOptInfo *baserel,
List *input_conds,
List **remote_conds,
List **local_conds)
{
ListCell *lc;
*remote_conds = NIL;
*local_conds = NIL;
foreach(lc, input_conds)
{
RestrictInfo *ri = lfirst_node(RestrictInfo, lc);
if (odbc_is_foreign_expr(root, baserel, ri->clause))
*remote_conds = lappend(*remote_conds, ri);
else
*local_conds = lappend(*local_conds, ri);
}
}
/*
* 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.
*/
bool
odbc_is_builtin(Oid oid)
{
return (oid < FirstGenbkiObjectId);
}
/*
* Deparse SELECT statement for given relation into buf.
*
* tlist contains the list of desired columns to be fetched from foreign server.
* For a base relation fpinfo->attrs_used is used to construct SELECT clause,
* hence the tlist is ignored for a base relation.
*
* remote_conds is the list of conditions to be deparsed into the WHERE clause
* (or, in the case of upper relations, into the HAVING clause).
*
* If params_list 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.
*
* pathkeys is the list of pathkeys to order the result by.
*
* is_subquery is the flag to indicate whether to deparse the specified
* relation as a subquery.
*
* List of columns selected is returned in retrieved_attrs.
*/
void
odbc_deparse_select_stmt_for_rel(StringInfo buf, PlannerInfo *root, RelOptInfo *rel,
List *tlist, List *remote_conds, List *pathkeys,
bool has_final_sort, bool has_limit, bool is_subquery,
List **retrieved_attrs)
{
deparse_expr_cxt context;
OdbcFdwRelationInfo *fpinfo = (OdbcFdwRelationInfo *) rel->fdw_private;
List *quals;
/*
* We handle relations for foreign tables, joins between those and upper
* relations.
*/
Assert(IS_SIMPLE_REL(rel) || IS_UPPER_REL(rel));
/* Fill portions of context common to upper, join and base relation */
context.buf = buf;
context.root = root;
context.foreignrel = rel;
context.q_char = fpinfo->q_char;
context.name_qualifier_char = fpinfo->name_qualifier_char;
context.scanrel = IS_UPPER_REL(rel) ? fpinfo->outerrel : rel;
/*
* For upper relations, the WHERE clause is built from the remote
* conditions of the underlying scan relation; otherwise, we can use the
* supplied list of remote conditions directly.
*/
if (IS_UPPER_REL(rel))
{
OdbcFdwRelationInfo *ofpinfo;
ofpinfo = (OdbcFdwRelationInfo *) fpinfo->outerrel->fdw_private;
quals = ofpinfo->remote_conds;
}
else
quals = remote_conds;
/* Construct SELECT clause */
odbc_deparse_select_sql(tlist, retrieved_attrs, &context);
/* Construct FROM and WHERE clauses */
odbc_deparse_from_expr(quals, &context);
}
/*
* Construct a simple SELECT statement that retrieves desired columns
* of the specified foreign table, and append it to "buf". The output
* contains just "SELECT ... ".
*
* We also create an integer List of the columns being retrieved, which is
* returned to *retrieved_attrs, unless we deparse the specified relation
* as a subquery.
*
* tlist is the list of desired columns. is_subquery is the flag to
* indicate whether to deparse the specified relation as a subquery.
* Read prologue of odbc_deparse_select_stmt_for_rel() for details.
*/
static void
odbc_deparse_select_sql(List *tlist, List **retrieved_attrs,
deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
RelOptInfo *foreignrel = context->foreignrel;
PlannerInfo *root = context->root;
OdbcFdwRelationInfo *fpinfo = (OdbcFdwRelationInfo *) foreignrel->fdw_private;
/*
* Construct SELECT list
*/
appendStringInfoString(buf, "SELECT ");
if (IS_UPPER_REL(foreignrel))
{
/*