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Add FORCE_NOT_NULL support to the file_fdw foreign data wrapper.

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This is implemented as a per-column boolean option, rather than trying
to match COPY's convention of a single option listing the column names.

Shigeru Hanada, reviewed by KaiGai Kohei
This commit is contained in:
Tom Lane
2011-09-16 16:35:51 -04:00
parent 9d306c66e6
commit 86a3f2d492
5 changed files with 185 additions and 12 deletions
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112
contrib/file_fdw/file_fdw.c
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@ -23,8 +23,10 @@
#include "foreign/fdwapi.h"
#include "foreign/foreign.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "optimizer/cost.h"
#include "utils/rel.h"
#include "utils/syscache.h"
PG_MODULE_MAGIC;
@ -40,6 +42,8 @@ struct FileFdwOption
/*
* Valid options for file_fdw.
* These options are based on the options for COPY FROM command.
* But note that force_not_null is handled as a boolean option attached to
* each column, not as a table option.
*
* Note: If you are adding new option for user mapping, you need to modify
* fileGetOptions(), which currently doesn't bother to look at user mappings.
@ -57,17 +61,12 @@ static struct FileFdwOption valid_options[] = {
{"escape", ForeignTableRelationId},
{"null", ForeignTableRelationId},
{"encoding", ForeignTableRelationId},
{"force_not_null", AttributeRelationId},
/*
* force_quote is not supported by file_fdw because it's for COPY TO.
*/
/*
* force_not_null is not supported by file_fdw. It would need a parser
* for list of columns, not to mention a way to check the column list
* against the table.
*/
/* Sentinel */
{NULL, InvalidOid}
};
@ -109,6 +108,7 @@ static void fileEndForeignScan(ForeignScanState *node);
static bool is_valid_option(const char *option, Oid context);
static void fileGetOptions(Oid foreigntableid,
char **filename, List **other_options);
static List *get_file_fdw_attribute_options(Oid relid);
static void estimate_costs(PlannerInfo *root, RelOptInfo *baserel,
const char *filename,
Cost *startup_cost, Cost *total_cost);
@ -145,6 +145,7 @@ file_fdw_validator(PG_FUNCTION_ARGS)
List *options_list = untransformRelOptions(PG_GETARG_DATUM(0));
Oid catalog = PG_GETARG_OID(1);
char *filename = NULL;
DefElem *force_not_null = NULL;
List *other_options = NIL;
ListCell *cell;
@ -198,7 +199,11 @@ file_fdw_validator(PG_FUNCTION_ARGS)
buf.data)));
}
/* Separate out filename, since ProcessCopyOptions won't allow it */
/*
* Separate out filename and force_not_null, since ProcessCopyOptions
* won't accept them. (force_not_null only comes in a boolean
* per-column flavor here.)
*/
if (strcmp(def->defname, "filename") == 0)
{
if (filename)
@ -207,6 +212,16 @@ file_fdw_validator(PG_FUNCTION_ARGS)
errmsg("conflicting or redundant options")));
filename = defGetString(def);
}
else if (strcmp(def->defname, "force_not_null") == 0)
{
if (force_not_null)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("conflicting or redundant options")));
force_not_null = def;
/* Don't care what the value is, as long as it's a legal boolean */
(void) defGetBoolean(def);
}
else
other_options = lappend(other_options, def);
}
@ -277,6 +292,7 @@ fileGetOptions(Oid foreigntableid,
options = list_concat(options, wrapper->options);
options = list_concat(options, server->options);
options = list_concat(options, table->options);
options = list_concat(options, get_file_fdw_attribute_options(foreigntableid));
/*
* Separate out the filename.
@ -306,6 +322,88 @@ fileGetOptions(Oid foreigntableid,
*other_options = options;
}
/*
* Retrieve per-column generic options from pg_attribute and construct a list
* of DefElems representing them.
*
* At the moment we only have "force_not_null", which should be combined into
* a single DefElem listing all such columns, since that's what COPY expects.
*/
static List *
get_file_fdw_attribute_options(Oid relid)
{
Relation rel;
TupleDesc tupleDesc;
AttrNumber natts;
AttrNumber attnum;
List *fnncolumns = NIL;
rel = heap_open(relid, AccessShareLock);
tupleDesc = RelationGetDescr(rel);
natts = tupleDesc->natts;
/* Retrieve FDW options for all user-defined attributes. */
for (attnum = 1; attnum <= natts; attnum++)
{
HeapTuple tuple;
Form_pg_attribute attr;
Datum datum;
bool isnull;
/* Skip dropped attributes. */
if (tupleDesc->attrs[attnum - 1]->attisdropped)
continue;
/*
* We need the whole pg_attribute tuple not just what is in the
* tupleDesc, so must do a catalog lookup.
*/
tuple = SearchSysCache2(ATTNUM,
RelationGetRelid(rel),
Int16GetDatum(attnum));
if (!HeapTupleIsValid(tuple))
elog(ERROR, "cache lookup failed for attribute %d of relation %u",
attnum, RelationGetRelid(rel));
attr = (Form_pg_attribute) GETSTRUCT(tuple);
datum = SysCacheGetAttr(ATTNUM,
tuple,
Anum_pg_attribute_attfdwoptions,
&isnull);
if (!isnull)
{
List *options = untransformRelOptions(datum);
ListCell *lc;
foreach(lc, options)
{
DefElem *def = (DefElem *) lfirst(lc);
if (strcmp(def->defname, "force_not_null") == 0)
{
if (defGetBoolean(def))
{
char *attname = pstrdup(NameStr(attr->attname));
fnncolumns = lappend(fnncolumns, makeString(attname));
}
}
/* maybe in future handle other options here */
}
}
ReleaseSysCache(tuple);
}
heap_close(rel, AccessShareLock);
/* Return DefElem only when some column(s) have force_not_null */
if (fnncolumns != NIL)
return list_make1(makeDefElem("force_not_null", (Node *) fnncolumns));
else
return NIL;
}
/*
* filePlanForeignScan
* Create a FdwPlan for a scan on the foreign table