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Allow postgres_fdw to ship extension funcs/operators for remote execution. 

The user can whitelist specified extension(s) in the foreign server's
options, whereupon we will treat immutable functions and operators of those
extensions as candidates to be sent for remote execution.

Whitelisting an extension in this way basically promises that the extension
exists on the remote server and behaves compatibly with the local instance.
We have no way to prove that formally, so we have to rely on the user to
get it right.  But this seems like something that people can usually get
right in practice.

We might in future allow functions and operators to be whitelisted
individually, but extension granularity is a very convenient special case,
so it got done first.

The patch as-committed lacks any regression tests, which is unfortunate,
but introducing dependencies on other extensions for testing purposes
would break "make installcheck" scenarios, which is worse.  I have some
ideas about klugy ways around that, but it seems like material for a
separate patch.  For the moment, leave the problem open.

Paul Ramsey, hacked up a bit more by me
This commit is contained in:
Tom Lane 2015-11-03 18:42:02 -05:00
parent ee44cb7566
commit d894941663
9 changed files with 427 additions and 91 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
contrib/postgres_fdw/Makefile
View File

@ -1,7 +1,7 @@
# contrib/postgres_fdw/Makefile
MODULE_big = postgres_fdw
OBJS = postgres_fdw.o option.o deparse.o connection.o $(WIN32RES)
OBJS = postgres_fdw.o option.o deparse.o connection.o shippable.o $(WIN32RES)
PGFILEDESC = "postgres_fdw - foreign data wrapper for PostgreSQL"
PG_CPPFLAGS = -I$(libpq_srcdir)

104
contrib/postgres_fdw/deparse.c
View File

@ -38,7 +38,6 @@
#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"
@ -102,7 +101,7 @@ typedef struct deparse_expr_cxt
static bool foreign_expr_walker(Node *node,
foreign_glob_cxt *glob_cxt,
foreign_loc_cxt *outer_cxt);
static bool is_builtin(Oid procid);
static char *deparse_type_name(Oid type_oid, int32 typemod);
/*
* Functions to construct string representation of a node tree.
@ -220,11 +219,12 @@ is_foreign_expr(PlannerInfo *root,
* 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.
* 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
foreign_expr_walker(Node *node,
@ -232,6 +232,7 @@ foreign_expr_walker(Node *node,
foreign_loc_cxt *outer_cxt)
{
bool check_type = true;
PgFdwRelationInfo *fpinfo;
foreign_loc_cxt inner_cxt;
Oid collation;
FDWCollateState state;
@ -240,6 +241,9 @@ foreign_expr_walker(Node *node,
if (node == NULL)
return true;
/* May need server info from baserel's fdw_private struct */
fpinfo = (PgFdwRelationInfo *) (glob_cxt->foreignrel->fdw_private);
/* Set up inner_cxt for possible recursion to child nodes */
inner_cxt.collation = InvalidOid;
inner_cxt.state = FDW_COLLATE_NONE;
@ -377,11 +381,11 @@ foreign_expr_walker(Node *node,
FuncExpr *fe = (FuncExpr *) node;
/*
* If function used by the expression is not built-in, it
* If function used by the expression is not shippable, it
* can't be sent to remote because it might have incompatible
* semantics on remote side.
*/
if (!is_builtin(fe->funcid))
if (!is_shippable(fe->funcid, ProcedureRelationId, fpinfo))
return false;
/*
@ -425,11 +429,11 @@ foreign_expr_walker(Node *node,
OpExpr *oe = (OpExpr *) node;
/*
* Similarly, only built-in operators can be sent to remote.
* (If the operator is, surely its underlying function is
* too.)
* Similarly, only shippable operators can be sent to remote.
* (If the operator is shippable, we assume its underlying
* function is too.)
*/
if (!is_builtin(oe->opno))
if (!is_shippable(oe->opno, OperatorRelationId, fpinfo))
return false;
/*
@ -467,9 +471,9 @@ foreign_expr_walker(Node *node,
ScalarArrayOpExpr *oe = (ScalarArrayOpExpr *) node;
/*
* Again, only built-in operators can be sent to remote.
* Again, only shippable operators can be sent to remote.
*/
if (!is_builtin(oe->opno))
if (!is_shippable(oe->opno, OperatorRelationId, fpinfo))
return false;
/*
@ -616,10 +620,10 @@ foreign_expr_walker(Node *node,
}
/*
* 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 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 && !is_builtin(exprType(node)))
if (check_type && !is_shippable(exprType(node), TypeRelationId, fpinfo))
return false;
/*
@ -672,27 +676,23 @@ foreign_expr_walker(Node *node,
}
/*
* Return true if given object is one of PostgreSQL's built-in objects.
* Convert type OID + typmod info into a type name we can ship to the remote
* server. Someplace else had better have verified that this type name is
* expected to be known on the remote end.
*
* 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.
* This is almost just format_type_with_typemod(), except that if left to its
* own devices, that function will make schema-qualification decisions based
* on the local search_path, which is wrong. We must schema-qualify all
* type names that are not in pg_catalog. We assume here that built-in types
* are all in pg_catalog and need not be qualified; otherwise, qualify.
*/
static bool
is_builtin(Oid oid)
static char *
deparse_type_name(Oid type_oid, int32 typemod)
{
return (oid < FirstBootstrapObjectId);
if (is_builtin(type_oid))
return format_type_with_typemod(type_oid, typemod);
else
return format_type_with_typemod_qualified(type_oid, typemod);
}
@ -1358,8 +1358,8 @@ deparseConst(Const *node, deparse_expr_cxt *context)
{
appendStringInfoString(buf, "NULL");
appendStringInfo(buf, "::%s",
format_type_with_typemod(node->consttype,
node->consttypmod));
deparse_type_name(node->consttype,
node->consttypmod));
return;
}
@ -1432,8 +1432,8 @@ deparseConst(Const *node, deparse_expr_cxt *context)
}
if (needlabel)
appendStringInfo(buf, "::%s",
format_type_with_typemod(node->consttype,
node->consttypmod));
deparse_type_name(node->consttype,
node->consttypmod));
}
/*
@ -1558,7 +1558,7 @@ deparseFuncExpr(FuncExpr *node, deparse_expr_cxt *context)
deparseExpr((Expr *) linitial(node->args), context);
appendStringInfo(buf, "::%s",
format_type_with_typemod(rettype, coercedTypmod));
deparse_type_name(rettype, coercedTypmod));
return;
}
@ -1753,8 +1753,8 @@ deparseRelabelType(RelabelType *node, deparse_expr_cxt *context)
deparseExpr(node->arg, context);
if (node->relabelformat != COERCE_IMPLICIT_CAST)
appendStringInfo(context->buf, "::%s",
format_type_with_typemod(node->resulttype,
node->resulttypmod));
deparse_type_name(node->resulttype,
node->resulttypmod));
}
/*
@ -1834,7 +1834,7 @@ deparseArrayExpr(ArrayExpr *node, deparse_expr_cxt *context)
/* 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));
deparse_type_name(node->array_typeid, -1));
}
/*
@ -1850,7 +1850,7 @@ printRemoteParam(int paramindex, Oid paramtype, int32 paramtypmod,
deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
char *ptypename = format_type_with_typemod(paramtype, paramtypmod);
char *ptypename = deparse_type_name(paramtype, paramtypmod);
appendStringInfo(buf, "$%d::%s", paramindex, ptypename);
}
@ -1876,7 +1876,7 @@ printRemotePlaceholder(Oid paramtype, int32 paramtypmod,
deparse_expr_cxt *context)
{
StringInfo buf = context->buf;
char *ptypename = format_type_with_typemod(paramtype, paramtypmod);
char *ptypename = deparse_type_name(paramtype, paramtypmod);
appendStringInfo(buf, "((SELECT null::%s)::%s)", ptypename, ptypename);
}
@ -1890,10 +1890,10 @@ void
appendOrderByClause(StringInfo buf, PlannerInfo *root, RelOptInfo *baserel,
List *pathkeys)
{
ListCell *lcell;
deparse_expr_cxt context;
int nestlevel;
char *delim = " ";
ListCell *lcell;
deparse_expr_cxt context;
int nestlevel;
char *delim = " ";
/* Set up context struct for recursion */
context.root = root;
@ -1907,8 +1907,8 @@ appendOrderByClause(StringInfo buf, PlannerInfo *root, RelOptInfo *baserel,
appendStringInfo(buf, " ORDER BY");
foreach(lcell, pathkeys)
{
PathKey *pathkey = lfirst(lcell);
Expr *em_expr;
PathKey *pathkey = lfirst(lcell);
Expr *em_expr;
em_expr = find_em_expr_for_rel(pathkey->pk_eclass, baserel);
Assert(em_expr != NULL);

54
contrib/postgres_fdw/option.c
View File

@ -19,6 +19,8 @@
#include "catalog/pg_foreign_table.h"
#include "catalog/pg_user_mapping.h"
#include "commands/defrem.h"
#include "commands/extension.h"
#include "utils/builtins.h"
/*
@ -124,6 +126,11 @@ postgres_fdw_validator(PG_FUNCTION_ARGS)
errmsg("%s requires a non-negative numeric value",
def->defname)));
}
else if (strcmp(def->defname, "extensions") == 0)
{
/* check list syntax, warn about uninstalled extensions */
(void) ExtractExtensionList(defGetString(def), true);
}
}
PG_RETURN_VOID();
@ -150,6 +157,8 @@ InitPgFdwOptions(void)
/* cost factors */
{"fdw_startup_cost", ForeignServerRelationId, false},
{"fdw_tuple_cost", ForeignServerRelationId, false},
/* shippable extensions */
{"extensions", ForeignServerRelationId, false},
/* updatable is available on both server and table */
{"updatable", ForeignServerRelationId, false},
{"updatable", ForeignTableRelationId, false},
@ -293,3 +302,48 @@ ExtractConnectionOptions(List *defelems, const char **keywords,
}
return i;
}
/*
* Parse a comma-separated string and return a List of the OIDs of the
* extensions named in the string. If any names in the list cannot be
* found, report a warning if warnOnMissing is true, else just silently
* ignore them.
*/
List *
ExtractExtensionList(const char *extensionsString, bool warnOnMissing)
{
List *extensionOids = NIL;
List *extlist;
ListCell *lc;
/* SplitIdentifierString scribbles on its input, so pstrdup first */
if (!SplitIdentifierString(pstrdup(extensionsString), ',', &extlist))
{
/* syntax error in name list */
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("parameter \"%s\" must be a list of extension names",
"extensions")));
}
foreach(lc, extlist)
{
const char *extension_name = (const char *) lfirst(lc);
Oid extension_oid = get_extension_oid(extension_name, true);
if (OidIsValid(extension_oid))
{
extensionOids = lappend_oid(extensionOids, extension_oid);
}
else if (warnOnMissing)
{
ereport(WARNING,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("extension \"%s\" is not installed",
extension_name)));
}
}
list_free(extlist);
return extensionOids;
}

38
contrib/postgres_fdw/postgres_fdw.c
View File

@ -50,40 +50,6 @@ PG_MODULE_MAGIC;
/* If no remote estimates, assume a sort costs 20% extra */
#define DEFAULT_FDW_SORT_MULTIPLIER 1.2
/*
* FDW-specific planner information kept in RelOptInfo.fdw_private for a
* foreign table. This information is collected by postgresGetForeignRelSize.
*/
typedef struct PgFdwRelationInfo
{
/* baserestrictinfo clauses, broken down into safe and unsafe subsets. */
List *remote_conds;
List *local_conds;
/* Bitmap of attr numbers we need to fetch from the remote server. */
Bitmapset *attrs_used;
/* Cost and selectivity of local_conds. */
QualCost local_conds_cost;
Selectivity local_conds_sel;
/* Estimated size and cost for a scan with baserestrictinfo quals. */
double rows;
int width;
Cost startup_cost;
Cost total_cost;
/* Options extracted from catalogs. */
bool use_remote_estimate;
Cost fdw_startup_cost;
Cost fdw_tuple_cost;
/* Cached catalog information. */
ForeignTable *table;
ForeignServer *server;
UserMapping *user; /* only set in use_remote_estimate mode */
} PgFdwRelationInfo;
/*
* Indexes of FDW-private information stored in fdw_private lists.
*
@ -409,6 +375,7 @@ postgresGetForeignRelSize(PlannerInfo *root,
fpinfo->use_remote_estimate = false;
fpinfo->fdw_startup_cost = DEFAULT_FDW_STARTUP_COST;
fpinfo->fdw_tuple_cost = DEFAULT_FDW_TUPLE_COST;
fpinfo->shippable_extensions = NIL;
foreach(lc, fpinfo->server->options)
{
@ -420,6 +387,9 @@ postgresGetForeignRelSize(PlannerInfo *root,
fpinfo->fdw_startup_cost = strtod(defGetString(def), NULL);
else if (strcmp(def->defname, "fdw_tuple_cost") == 0)
fpinfo->fdw_tuple_cost = strtod(defGetString(def), NULL);
else if (strcmp(def->defname, "extensions") == 0)
fpinfo->shippable_extensions =
ExtractExtensionList(defGetString(def), false);
}
foreach(lc, fpinfo->table->options)
{

43
contrib/postgres_fdw/postgres_fdw.h
View File

@ -20,6 +20,41 @@
#include "libpq-fe.h"
/*
* FDW-specific planner information kept in RelOptInfo.fdw_private for a
* foreign table. This information is collected by postgresGetForeignRelSize.
*/
typedef struct PgFdwRelationInfo
{
/* baserestrictinfo clauses, broken down into safe and unsafe subsets. */
List *remote_conds;
List *local_conds;
/* Bitmap of attr numbers we need to fetch from the remote server. */
Bitmapset *attrs_used;
/* Cost and selectivity of local_conds. */
QualCost local_conds_cost;
Selectivity local_conds_sel;
/* Estimated size and cost for a scan with baserestrictinfo quals. */
double rows;
int width;
Cost startup_cost;
Cost total_cost;
/* Options extracted from catalogs. */
bool use_remote_estimate;
Cost fdw_startup_cost;
Cost fdw_tuple_cost;
List *shippable_extensions; /* OIDs of whitelisted extensions */
/* Cached catalog information. */
ForeignTable *table;
ForeignServer *server;
UserMapping *user; /* only set in use_remote_estimate mode */
} PgFdwRelationInfo;
/* in postgres_fdw.c */
extern int set_transmission_modes(void);
extern void reset_transmission_modes(int nestlevel);
@ -37,6 +72,8 @@ extern void pgfdw_report_error(int elevel, PGresult *res, PGconn *conn,
extern int ExtractConnectionOptions(List *defelems,
const char **keywords,
const char **values);
extern List *ExtractExtensionList(const char *extensionsString,
bool warnOnMissing);
/* in deparse.c */
extern void classifyConditions(PlannerInfo *root,
@ -76,6 +113,10 @@ extern void deparseAnalyzeSql(StringInfo buf, Relation rel,
extern void deparseStringLiteral(StringInfo buf, const char *val);
extern Expr *find_em_expr_for_rel(EquivalenceClass *ec, RelOptInfo *rel);
extern void appendOrderByClause(StringInfo buf, PlannerInfo *root,
RelOptInfo *baserel, List *pathkeys);
RelOptInfo *baserel, List *pathkeys);
/* in shippable.c */
extern bool is_builtin(Oid objectId);
extern bool is_shippable(Oid objectId, Oid classId, PgFdwRelationInfo *fpinfo);
#endif /* POSTGRES_FDW_H */

214
contrib/postgres_fdw/shippable.c Normal file
View File

@ -0,0 +1,214 @@
/*-------------------------------------------------------------------------
*
* shippable.c
* Determine which database objects are shippable to a remote server.
*
* We need to determine whether particular functions, operators, and indeed
* data types are shippable to a remote server for execution --- that is,
* do they exist and have the same behavior remotely as they do locally?
* Built-in objects are generally considered shippable. Other objects can
* be shipped if they are white-listed by the user.
*
* Note: there are additional filter rules that prevent shipping mutable
* functions or functions using nonportable collations. Those considerations
* need not be accounted for here.
*
* Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
*
* IDENTIFICATION
* contrib/postgres_fdw/shippable.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "postgres_fdw.h"
#include "access/transam.h"
#include "catalog/dependency.h"
#include "utils/hsearch.h"
#include "utils/inval.h"
#include "utils/syscache.h"
/* Hash table for caching the results of shippability lookups */
static HTAB *ShippableCacheHash = NULL;
/*
* Hash key for shippability lookups. We include the FDW server OID because
* decisions may differ per-server. Otherwise, objects are identified by
* their (local!) OID and catalog OID.
*/
typedef struct
{
/* XXX we assume this struct contains no padding bytes */
Oid objid; /* function/operator/type OID */
Oid classid; /* OID of its catalog (pg_proc, etc) */
Oid serverid; /* FDW server we are concerned with */
} ShippableCacheKey;
typedef struct
{
ShippableCacheKey key; /* hash key - must be first */
bool shippable;
} ShippableCacheEntry;
/*
* Flush cache entries when pg_foreign_server is updated.
*
* We do this because of the possibility of ALTER SERVER being used to change
* a server's extensions option. We do not currently bother to check whether
* objects' extension membership changes once a shippability decision has been
* made for them, however.
*/
static void
InvalidateShippableCacheCallback(Datum arg, int cacheid, uint32 hashvalue)
{
HASH_SEQ_STATUS status;
ShippableCacheEntry *entry;
/*
* In principle we could flush only cache entries relating to the
* pg_foreign_server entry being outdated; but that would be more
* complicated, and it's probably not worth the trouble. So for now, just
* flush all entries.
*/
hash_seq_init(&status, ShippableCacheHash);
while ((entry = (ShippableCacheEntry *) hash_seq_search(&status)) != NULL)
{
if (hash_search(ShippableCacheHash,
(void *) &entry->key,
HASH_REMOVE,
NULL) == NULL)
elog(ERROR, "hash table corrupted");
}
}
/*
* Initialize the backend-lifespan cache of shippability decisions.
*/
static void
InitializeShippableCache(void)
{
HASHCTL ctl;
/* Create the hash table. */
MemSet(&ctl, 0, sizeof(ctl));
ctl.keysize = sizeof(ShippableCacheKey);
ctl.entrysize = sizeof(ShippableCacheEntry);
ShippableCacheHash =
hash_create("Shippability cache", 256, &ctl, HASH_ELEM | HASH_BLOBS);
/* Set up invalidation callback on pg_foreign_server. */
CacheRegisterSyscacheCallback(FOREIGNSERVEROID,
InvalidateShippableCacheCallback,
(Datum) 0);
}
/*
* Returns true if given object (operator/function/type) is shippable
* according to the server options.
*
* Right now "shippability" is exclusively a function of whether the object
* belongs to an extension declared by the user. In the future we could
* additionally have a whitelist of functions/operators declared one at a time.
*/
static bool
lookup_shippable(Oid objectId, Oid classId, PgFdwRelationInfo *fpinfo)
{
Oid extensionOid;
/*
* Is object a member of some extension? (Note: this is a fairly
* expensive lookup, which is why we try to cache the results.)
*/
extensionOid = getExtensionOfObject(classId, objectId);
/* If so, is that extension in fpinfo->shippable_extensions? */
if (OidIsValid(extensionOid) &&
list_member_oid(fpinfo->shippable_extensions, extensionOid))
return true;
return false;
}
/*
* 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 deparse_type_name might incorrectly fail to schema-qualify their names.
* 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
is_builtin(Oid objectId)
{
return (objectId < FirstBootstrapObjectId);
}
/*
* is_shippable
* Is this object (function/operator/type) shippable to foreign server?
*/
bool
is_shippable(Oid objectId, Oid classId, PgFdwRelationInfo *fpinfo)
{
ShippableCacheKey key;
ShippableCacheEntry *entry;
/* Built-in objects are presumed shippable. */
if (is_builtin(objectId))
return true;
/* Otherwise, give up if user hasn't specified any shippable extensions. */
if (fpinfo->shippable_extensions == NIL)
return false;
/* Initialize cache if first time through. */
if (!ShippableCacheHash)
InitializeShippableCache();
/* Set up cache hash key */
key.objid = objectId;
key.classid = classId;
key.serverid = fpinfo->server->serverid;
/* See if we already cached the result. */
entry = (ShippableCacheEntry *)
hash_search(ShippableCacheHash,
(void *) &key,
HASH_FIND,
NULL);
if (!entry)
{
/* Not found in cache, so perform shippability lookup. */
bool shippable = lookup_shippable(objectId, classId, fpinfo);
/*
* Don't create a new hash entry until *after* we have the shippable
* result in hand, as the underlying catalog lookups might trigger a
* cache invalidation.
*/
entry = (ShippableCacheEntry *)
hash_search(ShippableCacheHash,
(void *) &key,
HASH_ENTER,
NULL);
entry->shippable = shippable;
}
return entry->shippable;
}

46
doc/src/sgml/postgres-fdw.sgml
View File

@ -264,6 +264,46 @@
</sect3>
<sect3>
<title>Remote Execution Options</title>
<para>
By default, only <literal>WHERE</> clauses using built-in operators and
functions will be considered for execution on the remote server. Clauses
involving non-built-in functions are checked locally after rows are
fetched. If such functions are available on the remote server and can be
relied on to produce the same results as they do locally, performance can
be improved by sending such <literal>WHERE</> clauses for remote
execution. This behavior can be controlled using the following option:
</para>
<variablelist>
<varlistentry>
<term><literal>extensions</literal></term>
<listitem>
<para>
This option is a comma-separated list of names
of <productname>PostgreSQL</> extensions that are installed, in
compatible versions, on both the local and remote servers. Functions
and operators that are immutable and belong to a listed extension will
be considered shippable to the remote server.
This option can only be specified for foreign servers, not per-table.
</para>
</listitem>
</varlistentry>
</variablelist>
<para>
When using the <literal>extensions</literal> option, <emphasis>it is the
user's responsibility</> that the listed extensions exist and behave
identically on both the local and remote servers. Otherwise, remote
queries may fail or behave unexpectedly.
</para>
</sect3>
<sect3>
<title>Updatability Options</title>
@ -427,8 +467,10 @@
execution, and by not retrieving table columns that are not needed for
the current query. To reduce the risk of misexecution of queries,
<literal>WHERE</> clauses are not sent to the remote server unless they use
only built-in data types, operators, and functions. Operators and
functions in the clauses must be <literal>IMMUTABLE</> as well.
only data types, operators, and functions that are built-in or belong to an
extension that's listed in the foreign server's <literal>extensions</>
option. Operators and functions in such clauses must
be <literal>IMMUTABLE</> as well.
</para>
<para>

16
src/backend/utils/adt/format_type.c
View File

@ -97,7 +97,8 @@ format_type_be(Oid type_oid)
}
/*
* This version returns a name which is always qualified.
* This version returns a name that is always qualified (unless it's one
* of the SQL-keyword type names, such as TIMESTAMP WITH TIME ZONE).
*/
char *
format_type_be_qualified(Oid type_oid)
@ -114,6 +115,19 @@ format_type_with_typemod(Oid type_oid, int32 typemod)
return format_type_internal(type_oid, typemod, true, false, false);
}
/*
* This version allows a nondefault typemod to be specified, and forces
* qualification of normal type names.
*/
char *
format_type_with_typemod_qualified(Oid type_oid, int32 typemod)
{
return format_type_internal(type_oid, typemod, true, false, true);
}
/*
* Common workhorse.
*/
static char *
format_type_internal(Oid type_oid, int32 typemod,
bool typemod_given, bool allow_invalid,

1
src/include/utils/builtins.h
View File

@ -1105,6 +1105,7 @@ extern Datum format_type(PG_FUNCTION_ARGS);
extern char *format_type_be(Oid type_oid);
extern char *format_type_be_qualified(Oid type_oid);
extern char *format_type_with_typemod(Oid type_oid, int32 typemod);
extern char *format_type_with_typemod_qualified(Oid type_oid, int32 typemod);
extern Datum oidvectortypes(PG_FUNCTION_ARGS);
extern int32 type_maximum_size(Oid type_oid, int32 typemod);