greenplumn gp_exttable_fdw 源码
greenplumn gp_exttable_fdw 代码
文件路径：/gpcontrib/gp_exttable_fdw/gp_exttable_fdw.c
/*-------------------------------------------------------------------------
*
* gp_exttable_fdw.c
* Shim layer between legacy GPDB external table API and the Foreign
* Data Wrapper API
*
* This implements the FDW routines expected by PostgreSQL backend code,
* to plan and execute queries on external tables. The FDW routines
* call into the corresponding legacy external table API functions to do
* the real work, IterateForeignScan for example just calls
* external_getnext().
*
* Portions Copyright (c) 2007-2008, Greenplum inc
* Portions Copyright (c) 2012-Present VMware, Inc. or its affiliates.
*
*
* IDENTIFICATION
* gpcontrib/gp_exttable_fdw/gp_exttable_fdw.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "extaccess.h"
#include "fmgr.h"
#include "nodes/plannodes.h"
#include "access/external.h"
#include "access/reloptions.h"
#include "access/relscan.h"
#include "access/table.h"
#include "cdb/cdbvars.h"
#include "catalog/pg_authid.h"
#include "catalog/pg_extprotocol.h"
#include "catalog/pg_foreign_server.h"
#include "catalog/pg_foreign_table.h"
#include "commands/defrem.h"
#include "commands/copy.h"
#include "cdb/cdbsreh.h"
#include "foreign/fdwapi.h"
#include "funcapi.h"
#include "nodes/execnodes.h"
#include "nodes/makefuncs.h"
#include "nodes/pathnodes.h"
#include "optimizer/cost.h"
#include "optimizer/optimizer.h"
#include "optimizer/pathnode.h"
#include "optimizer/planmain.h"
#include "optimizer/restrictinfo.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/guc.h"
#include "utils/partcache.h"
#include "utils/syscache.h"
#include "utils/uri.h"
PG_MODULE_MAGIC;
#define GP_EXTTABLE_ATTRNUM 12
extern Datum gp_exttable_fdw_handler(PG_FUNCTION_ARGS);
extern Datum gp_exttable_permission_check(PG_FUNCTION_ARGS);
extern Datum pg_exttable(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(gp_exttable_fdw_handler);
PG_FUNCTION_INFO_V1(gp_exttable_permission_check);
PG_FUNCTION_INFO_V1(pg_exttable);
/*
* PGExtTableEntry is used in pg_exttable(). It reflects each external
* table entry in the foreign table catalog.
*/
typedef struct PGExtTableEntry
{
Oid reloid;
Oid serveroid;
List *ftoptions;
} PGExtTableEntry;
/*
* PGExtTableEntriesContext is used in pg_exttable() as user_fctx.
*/
typedef struct PGExtTableEntriesContext
{
int entryIdx;
List *ftentries;
} PGExtTableEntriesContext;
typedef struct
{
FileScanDescData *ess_ScanDesc;
ExternalSelectDesc externalSelectDesc;
} exttable_fdw_state;
static void cost_externalscan(ForeignPath *path, PlannerInfo *root,
RelOptInfo *baserel, ParamPathInfo *param_info);
/*
* strListToArray - String Value to Text array datum
*/
static Datum
strListToArray(List *stringlist)
{
ArrayBuildState *astate = NULL;
ListCell *cell;
foreach(cell, stringlist)
{
Value *val = lfirst(cell);
astate = accumArrayResult(astate, CStringGetTextDatum(strVal(val)),
false, TEXTOID,
CurrentMemoryContext);
}
if (astate)
return makeArrayResult(astate, CurrentMemoryContext);
return PointerGetDatum(NULL);
}
/*
* formatOptionsToTextDatum
* Convert format options to text datum. The text datum format is same with
* the original pg_exttable catalog's fmtopt field.
*/
static Datum
formatOptionsToTextDatum(List *options, char formattype)
{
ListCell *option;
Datum result;
StringInfoData cfbuf;
initStringInfo(&cfbuf);
if (fmttype_is_text(formattype) || fmttype_is_csv(formattype))
{
bool isfirst = true;
/*
* Note: the order of the options should be same with the original
* pg_exttable catalog's fmtopt field.
*/
foreach(option, options)
{
DefElem *defel = (DefElem *) lfirst(option);
char *key = defel->defname;
char *val = (char *) defGetString(defel);
if (strcmp(defel->defname, "format") == 0)
continue;
if (isfirst)
isfirst = false;
else
appendStringInfo(&cfbuf, " ");
if (strcmp(defel->defname, "header") == 0)
appendStringInfo(&cfbuf, "header");
else if (strcmp(defel->defname, "fill_missing_fields") == 0)
appendStringInfo(&cfbuf, "fill missing fields");
else if (strcmp(defel->defname, "force_not_null") == 0)
appendStringInfo(&cfbuf, "force not null %s", val);
else if (strcmp(defel->defname, "force_quote") == 0)
appendStringInfo(&cfbuf, "force quote %s", val);
else
appendStringInfo(&cfbuf, "%s '%s'", key, val);
}
}
else
{
foreach(option, options)
{
DefElem *defel = (DefElem *) lfirst(option);
char *key = defel->defname;
char *val = (char *) defGetString(defel);
appendStringInfo(&cfbuf, "%s '%s'", key, val);
}
}
result = CStringGetTextDatum(cfbuf.data);
pfree(cfbuf.data);
return result;
}
/*
* Use the pg_exttable UDF to extract pg_exttable catalog info for
* extension compatibility.
*
* pg_exttable catalog was removed because we use the FDW to implement
* external table now. But other extensions may still rely on the pg_exttable
* catalog. So we create a view base on this UDF to extract pg_exttable catalog
* info.
*/
Datum pg_exttable(PG_FUNCTION_ARGS)
{
FuncCallContext *funcctx;
PGExtTableEntriesContext *context;
Datum values[GP_EXTTABLE_ATTRNUM];
bool nulls[GP_EXTTABLE_ATTRNUM] = {false};
/*
* First call setup
*/
if (SRF_IS_FIRSTCALL())
{
MemoryContext oldcontext;
Relation pg_foreign_table_rel;
ScanKeyData ftkey;
SysScanDesc ftscan;
HeapTuple fttuple;
Form_pg_foreign_table fttableform;
List *ftentries = NIL;
Oid extserver;
funcctx = SRF_FIRSTCALL_INIT();
oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
/* Build tuple descriptor */
TupleDesc tupdesc = CreateTemplateTupleDesc(GP_EXTTABLE_ATTRNUM);
TupleDescInitEntry(tupdesc, (AttrNumber) 1, "reloid", OIDOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 2, "urilocation", TEXTARRAYOID, -1, 1);
TupleDescInitEntry(tupdesc, (AttrNumber) 3, "execlocation", TEXTARRAYOID, -1, 1);
TupleDescInitEntry(tupdesc, (AttrNumber) 4, "fmttype", CHAROID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 5, "fmtopts", TEXTOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 6, "options", TEXTARRAYOID, -1, 1);
TupleDescInitEntry(tupdesc, (AttrNumber) 7, "command", TEXTOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 8, "rejectlimit", INT4OID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 9, "rejectlimittype", CHAROID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 10, "logerrors", CHAROID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 11, "encoding", INT4OID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 12, "writable", BOOLOID, -1, 0);
funcctx->tuple_desc = BlessTupleDesc(tupdesc);
extserver = get_foreign_server_oid(GP_EXTTABLE_SERVER_NAME, false);
/* Retrieve external table in foreign table catalog */
pg_foreign_table_rel = table_open(ForeignTableRelationId, AccessShareLock);
ScanKeyInit(&ftkey,
Anum_pg_foreign_table_ftserver,
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(extserver));
ftscan = systable_beginscan(pg_foreign_table_rel, InvalidOid,
false, NULL, 1, &ftkey);
while (HeapTupleIsValid(fttuple = systable_getnext(ftscan)))
{
Datum ftoptions;
bool isNull;
PGExtTableEntry *entry= (PGExtTableEntry *) palloc0(sizeof(PGExtTableEntry));
fttableform = (Form_pg_foreign_table) GETSTRUCT(fttuple);
entry->reloid = fttableform->ftrelid;
entry->serveroid = fttableform->ftserver;
/* get the foreign table options */
ftoptions = heap_getattr(fttuple,
Anum_pg_foreign_table_ftoptions,
RelationGetDescr(pg_foreign_table_rel),
&isNull);
if (!isNull)
entry->ftoptions = untransformRelOptions(ftoptions);
ftentries = lappend(ftentries, entry);
}
systable_endscan(ftscan);
table_close(pg_foreign_table_rel, AccessShareLock);
context = (PGExtTableEntriesContext *)palloc0(sizeof(PGExtTableEntriesContext));
context->entryIdx = 0;
context->ftentries = ftentries;
funcctx->user_fctx = (void *) context;
MemoryContextSwitchTo(oldcontext);
}
funcctx = SRF_PERCALL_SETUP();
context = (PGExtTableEntriesContext *) funcctx->user_fctx;
while (context->entryIdx < list_length(context->ftentries))
{
PGExtTableEntry *entry;
ExtTableEntry *extentry;
Datum datum;
HeapTuple tuple;
Datum result;
entry = (PGExtTableEntry *)list_nth(context->ftentries, context->entryIdx);
context->entryIdx++;
extentry = GetExtFromForeignTableOptions(entry->ftoptions, entry->reloid);
memset(values, 0, sizeof(values));
memset(nulls, 0, sizeof(nulls));
/* reloid */
values[0] = ObjectIdGetDatum(entry->reloid);
/* urilocations */
datum = strListToArray(extentry->urilocations);
if (DatumGetPointer(datum) != NULL)
values[1] = datum;
else
nulls[1] = true;
/* execlocations */
datum = strListToArray(extentry->execlocations);
if (DatumGetPointer(datum) != NULL)
values[2] = datum;
else
nulls[2] = true;
/* fmtcode */
values[3] = CharGetDatum(extentry->fmtcode);
/* fmtopts */
if (extentry->options)
values[4] = formatOptionsToTextDatum(extentry->options, extentry->fmtcode);
else
nulls[4] = true;
/*
* options. Since our document not contains the OPTION caluse, so we
* assume no external table options in used for now. Except
* gpextprotocol.c.
*/
nulls[5] = true;
/* command */
if (extentry->command)
values[6] = CStringGetTextDatum(extentry->command);
else
nulls[6] = true;
/* rejectlimit */
values[7] = Int32GetDatum(extentry->rejectlimit);
if (values[7] == -1)
nulls[7] = true;
/* rejectlimittype */
values[8] = CharGetDatum(extentry->rejectlimittype);
if (values[8] == -1)
nulls[8] = true;
/* logerrors */
values[9] = CharGetDatum(extentry->logerrors);
/* encoding */
values[10] = Int32GetDatum(extentry->encoding);
/* iswritable */
values[11] = BoolGetDatum(extentry->iswritable);
tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
result = HeapTupleGetDatum(tuple);
SRF_RETURN_NEXT(funcctx, result);
}
SRF_RETURN_DONE(funcctx);
}
/* FDW validator for external tables */
Datum
gp_exttable_permission_check(PG_FUNCTION_ARGS)
{
List *options_list = untransformRelOptions(PG_GETARG_DATUM(0));
if (!superuser() && Gp_role == GP_ROLE_DISPATCH)
{
/*----------
* check permissions to create this external table.
*
* - Always allow if superuser.
* - Never allow EXECUTE or 'file' exttables if not superuser.
* - Allow http, gpfdist or gpfdists tables if pg_auth has the right
* permissions for this role and for this type of table
*----------
*/
ListCell *lc;
bool iswritable = false;
foreach(lc, options_list)
{
DefElem *def = (DefElem *) lfirst(lc);
if (pg_strcasecmp(def->defname, "command") == 0)
{
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("must be superuser to create an EXECUTE external web table")));
}
else if (pg_strcasecmp(def->defname, "is_writable") == 0)
{
iswritable = defGetBoolean(def);
}
}
foreach(lc, options_list)
{
DefElem *def = (DefElem *) lfirst(lc);
if (pg_strcasecmp(def->defname, "location_uris") == 0)
{
List *location_list = TokenizeLocationUris(defGetString(def));
ListCell *first_uri = list_head(location_list);
Value *v = lfirst(first_uri);
char *uri_str = pstrdup(v->val.str);
Uri *uri = ParseExternalTableUri(uri_str);
/* Assert(exttypeDesc->exttabletype == EXTTBL_TYPE_LOCATION); */
if (uri->protocol == URI_FILE)
{
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("must be superuser to create an external table with a file protocol")));
}
else
{
/*
* Check if this role has the proper 'gpfdist', 'gpfdists' or
* 'http' permissions in pg_auth for creating this table.
*/
bool isnull;
HeapTuple tuple;
tuple = SearchSysCache1(AUTHOID, ObjectIdGetDatum(GetUserId()));
if (!HeapTupleIsValid(tuple))
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_OBJECT),
errmsg("role \"%s\" does not exist (in DefineExternalRelation)",
GetUserNameFromId(GetUserId(), false))));
if ((uri->protocol == URI_GPFDIST || uri->protocol == URI_GPFDISTS) && iswritable)
{
Datum d_wextgpfd;
bool createwextgpfd;
d_wextgpfd = SysCacheGetAttr(AUTHOID, tuple,
Anum_pg_authid_rolcreatewextgpfd,
&isnull);
createwextgpfd = (isnull ? false : DatumGetBool(d_wextgpfd));
if (!createwextgpfd)
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("permission denied: no privilege to create a writable gpfdist(s) external table")));
}
else if ((uri->protocol == URI_GPFDIST || uri->protocol == URI_GPFDISTS) && !iswritable)
{
Datum d_rextgpfd;
bool createrextgpfd;
d_rextgpfd = SysCacheGetAttr(AUTHOID, tuple,
Anum_pg_authid_rolcreaterextgpfd,
&isnull);
createrextgpfd = (isnull ? false : DatumGetBool(d_rextgpfd));
if (!createrextgpfd)
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("permission denied: no privilege to create a readable gpfdist(s) external table")));
}
else if (uri->protocol == URI_HTTP && !iswritable)
{
Datum d_exthttp;
bool createrexthttp;
d_exthttp = SysCacheGetAttr(AUTHOID, tuple,
Anum_pg_authid_rolcreaterexthttp,
&isnull);
createrexthttp = (isnull ? false : DatumGetBool(d_exthttp));
if (!createrexthttp)
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
errmsg("permission denied: no privilege to create an http external table")));
}
else if (uri->protocol == URI_CUSTOM)
{
Oid ownerId = GetUserId();
char *protname = uri->customprotocol;
Oid ptcId = get_extprotocol_oid(protname, false);
AclResult aclresult;
/* Check we have the right permissions on this protocol */
if (!pg_extprotocol_ownercheck(ptcId, ownerId))
{
AclMode mode = (iswritable ? ACL_INSERT : ACL_SELECT);
aclresult = pg_extprotocol_aclcheck(ptcId, ownerId, mode);
if (aclresult != ACLCHECK_OK)
aclcheck_error(aclresult, OBJECT_EXTPROTOCOL, protname);
}
}
else
ereport(ERROR,
(errcode(ERRCODE_INTERNAL_ERROR),
errmsg("internal error in DefineExternalRelation"),
errdetail("Protocol is %d, writable is %d.",
uri->protocol, iswritable)));
ReleaseSysCache(tuple);
}
FreeExternalTableUri(uri);
pfree(uri_str);
break;
}
}
}
PG_RETURN_VOID();
}
static void
exttable_GetForeignRelSize(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid)
{
set_baserel_size_estimates(root, baserel);
}
static void
exttable_GetForeignPaths(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid)
{
ForeignPath *pathnode;
ExternalScanInfo *externalscan_info;
ExtTableEntry *extEntry;
extEntry = GetExtTableEntry(foreigntableid);
/* it should be an external rel... */
Assert(baserel->rtekind == RTE_RELATION);
Assert(extEntry->execlocations != NIL);
externalscan_info = MakeExternalScanInfo(extEntry);
pathnode = create_foreignscan_path(root,
baserel,
NULL, /* default pathtarget */
0, /* rows, filled in later */
0, /* startup_cost, later */
0, /* total_cost, later */
NIL, /* external scan has unordered result */
NULL, /* no outer rel either */
NULL, /* no extra plan */
list_make1(externalscan_info));
pathnode->path.locus = cdbpathlocus_from_baserel(root, baserel);
pathnode->path.motionHazard = false;
/*
* Mark external tables as non-rescannable. While rescan is possible,
* it can lead to surprising results if the external table produces
* different results when invoked twice.
*/
pathnode->path.rescannable = false;
pathnode->path.sameslice_relids = baserel->relids;
cost_externalscan(pathnode, root, baserel, pathnode->path.param_info);
add_path(baserel, (Path *) pathnode);
set_cheapest(baserel);
}
/*
* create_externalscan_plan
* Returns an externalscan plan for the base relation scanned by 'best_path'
* with restriction clauses 'scan_clauses' and targetlist 'tlist'.
*
* The external plan also includes the data format specification and file
* location specification. Here is where we do the mapping of external file
* to segment database and add it to the plan (or bail out of the mapping
* rules are broken)
*
* Mapping rules
* -------------
* - 'file' protocol: each location (URI of local file) gets mapped to one
* and one only primary segdb.
* - 'http' protocol: each location (URI of http server) gets mapped to one
* and one only primary segdb.
* - 'gpfdist' and 'gpfdists' protocols: all locations (URI of gpfdist(s) client) are mapped
* to all primary segdbs. If there are less URIs than
* segdbs (usually the case) the URIs are duplicated
* so that there will be one for each segdb. However, if
* the GUC variable gp_external_max_segs is set to a num
* less than (total segdbs/total URIs) then we make sure
* that no URI gets mapped to more than this GUC number by
* skipping some segdbs randomly.
* - 'exec' protocol: all segdbs get mapped to execute the command (this is
* soon to be changed though).
*/
static ForeignScan *
exttable_GetForeignPlan(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid,
ForeignPath *best_path,
List *tlist,
List *scan_clauses,
Plan *outer_plan)
{
Index scan_relid = best_path->path.parent->relid;
ForeignScan *scan_plan;
Assert(scan_relid > 0);
/* Reduce RestrictInfo list to bare expressions; ignore pseudoconstants */
scan_clauses = extract_actual_clauses(scan_clauses, false);
scan_plan = make_foreignscan(tlist,
scan_clauses,
scan_relid,
NIL, /* fdw_exprs */
best_path->fdw_private,
NIL, /* fdw_scan_tlist */
NIL, /* fdw_recheck_quals */
NULL /* outer_plan */);
return scan_plan;
}
static void
exttable_BeginForeignScan(ForeignScanState *node,
int eflags)
{
ForeignScan *scan;
Relation currentRelation;
FileScanDesc currentScanDesc;
ExternalSelectDesc externalSelectDesc;
ExternalScanInfo *externalscan_info;
exttable_fdw_state *fdw_state;
scan = (ForeignScan *) node->ss.ps.plan;
externalscan_info = (ExternalScanInfo *) linitial(scan->fdw_private);
Assert(IsA(externalscan_info, ExternalScanInfo));
currentRelation = node->ss.ss_currentRelation;
if (!currentRelation)
elog(ERROR, "external table scan without a current relation");
currentScanDesc = external_beginscan(currentRelation,
externalscan_info->scancounter,
externalscan_info->uriList,
externalscan_info->fmtType,
externalscan_info->isMasterOnly,
externalscan_info->rejLimit,
externalscan_info->rejLimitInRows,
externalscan_info->logErrors,
externalscan_info->encoding,
externalscan_info->extOptions);
externalSelectDesc = external_getnext_init(&node->ss.ps);
if (gp_external_enable_filter_pushdown)
externalSelectDesc->filter_quals = node->ss.ps.plan->qual;
fdw_state = palloc(sizeof(exttable_fdw_state));
fdw_state->ess_ScanDesc = currentScanDesc;
fdw_state->externalSelectDesc = externalSelectDesc;
node->fdw_state = fdw_state;
}
static bool
ExternalConstraintCheck(TupleTableSlot *slot, FileScanDesc scandesc, EState *estate)
{
Relation rel = scandesc->fs_rd;
TupleConstr *constr = rel->rd_att->constr;
ConstrCheck *check = constr->check;
uint16 ncheck = constr->num_check;
ExprContext *econtext = NULL;
MemoryContext oldContext = NULL;
/* No constraints */
if (ncheck == 0)
{
return true;
}
/*
* Build expression nodetrees for rel's constraint expressions.
* Keep them in the per-query memory context so they'll survive throughout the query.
*/
if (scandesc->fs_constraintExprs == NULL)
{
oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
scandesc->fs_constraintExprs =
(ExprState **) palloc(ncheck * sizeof(ExprState *));
for (int i = 0; i < ncheck; i++)
{
/* ExecQual wants implicit-AND form */
List *qual = make_ands_implicit(stringToNode(check[i].ccbin));
scandesc->fs_constraintExprs[i] =
ExecPrepareExpr((Expr *) qual, estate);
}
MemoryContextSwitchTo(oldContext);
}
/*
* We will use the EState's per-tuple context for evaluating constraint
* expressions (creating it if it's not already there).
*/
econtext = GetPerTupleExprContext(estate);
/* Arrange for econtext's scan tuple to be the tuple under test */
econtext->ecxt_scantuple = slot;
/* And evaluate the constraints */
for (int i = 0; i < ncheck; i++)
{
ExprState *qual = scandesc->fs_constraintExprs[i];
if (!ExecCheck(qual, econtext))
return false;
}
return true;
}
/*
* Check whether a row matches the partition constraint.
*/
static bool
ExternalPartitionCheck(TupleTableSlot *slot, FileScanDesc scandesc, EState *estate)
{
Relation rel = scandesc->fs_rd;
ExprContext *econtext;
/*
* Build expression nodetrees for rel's constraint expressions.
* Keep them in the per-query memory context so they'll survive throughout the query.
*/
if (scandesc->fs_partitionCheckExpr == NULL)
{
List *partition_check;
MemoryContext oldContext;
oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
partition_check = RelationGetPartitionQual(rel);
scandesc->fs_partitionCheckExpr = ExecPrepareCheck(partition_check, estate);
MemoryContextSwitchTo(oldContext);
}
/*
* We will use the EState's per-tuple context for evaluating constraint
* expressions (creating it if it's not already there).
*/
econtext = GetPerTupleExprContext(estate);
/* Arrange for econtext's scan tuple to be the tuple under test */
econtext->ecxt_scantuple = slot;
return ExecCheck(scandesc->fs_partitionCheckExpr, econtext);
}
static TupleTableSlot *
exttable_IterateForeignScan(ForeignScanState *node)
{
EState *estate = node->ss.ps.state;
exttable_fdw_state *fdw_state = (exttable_fdw_state *) node->fdw_state;
TupleTableSlot *slot = node->ss.ss_ScanTupleSlot;
HeapTuple tuple;
MemoryContext oldcxt;
/*
* XXX: ForeignNext() calls us in a short-lived memory context, which
* seems like a good idea. However external_getnext() allocates some stuff
* that needs to live longer. At least on the first call. The old
* ExternalScan plan node used to run in a long-lived context, which seems
* a bit dangerous to me, but I guess that external_getnext() and all the
* external protocols are careful not to leak memory.
*/
oldcxt = MemoryContextSwitchTo(estate->es_query_cxt);
for (;;)
{
tuple = external_getnext(fdw_state->ess_ScanDesc,
ForwardScanDirection, /* FIXME: foreign scans don't support backward scans, I think? */
fdw_state->externalSelectDesc);
if (!tuple)
{
ExecClearTuple(slot);
break;
}
ExecStoreHeapTuple(tuple, slot, true);
/*
* If this is a partition in a partitioned table, check each row against
* the partition qual, and skip rows that don't belong in this partition.
* Foreign tables are not required to enforce that, but that has been
* the historical behavior for external tables.
*/
if (fdw_state->ess_ScanDesc->fs_isPartition &&
!ExternalPartitionCheck(slot, fdw_state->ess_ScanDesc, estate))
continue;
/*
* Similarly, check CHECK constraints and skip rows that don't satisfy
* them. Foreign tables are not required required to enforce CHECK
* constraints either, they are merely hints to the optimizer, but it
* is allowed. (In GPDB 6 and below, partition quals were stored in the
* catalogs as CHECK constraints, so this was needed to check the
* partition quals.)
*/
if (fdw_state->ess_ScanDesc->fs_hasConstraints &&
!ExternalConstraintCheck(slot, fdw_state->ess_ScanDesc, estate))
continue;
break;
}
MemoryContextSwitchTo(oldcxt);
return slot;
}
static void
exttable_ReScanForeignScan(ForeignScanState *node)
{
exttable_fdw_state *fdw_state = (exttable_fdw_state *) node->fdw_state;
external_rescan(fdw_state->ess_ScanDesc);
}
static void
exttable_EndForeignScan(ForeignScanState *node)
{
exttable_fdw_state *fdw_state = (exttable_fdw_state *) node->fdw_state;
if (node->ss.ps.squelched)
external_stopscan(fdw_state->ess_ScanDesc);
/*
* report Sreh results if external web table execute on coordinator with reject limit.
* if external web table execute on segment, these messages are printed
* in cdbdisp_sumRejectedRows()
*/
if (Gp_role == GP_ROLE_DISPATCH) {
CopyState cstate = fdw_state->ess_ScanDesc->fs_pstate;
if (cstate && cstate->cdbsreh)
{
CdbSreh *cdbsreh = cstate->cdbsreh;
uint64 total_rejected_from_qd = cdbsreh->rejectcount;
if (total_rejected_from_qd > 0)
ReportSrehResults(cdbsreh, total_rejected_from_qd);
}
}
external_endscan(fdw_state->ess_ScanDesc);
}
/* ModifyTable support */
static int
exttable_IsForeignRelUpdatable(Relation rel)
{
ExtTableEntry *extentry;
bool iswritable;
extentry = GetExtTableEntry(RelationGetRelid(rel));
iswritable = extentry->iswritable;
pfree(extentry);
return iswritable ? (1 << CMD_INSERT) : 0;
}
static void
exttable_BeginForeignModify(ModifyTableState *mtstate,
ResultRelInfo *rinfo,
List *fdw_private,
int subplan_index,
int eflags)
{
/*
* Do nothing in EXPLAIN (no ANALYZE) case. resultRelInfo->ri_FdwState
* stays NULL.
*/
if (eflags & EXEC_FLAG_EXPLAIN_ONLY)
return;
/*
* This would be the natural place to call external_insert_init(), but we
* delay that until the first actual insert. That's because we don't want
* to open the external resource if we don't end up actually inserting any
* rows in this segment. In particular, we don't want to initialize the
* external resource in the QD node, when all the actual insertions happen
* in the segments.
*/
}
static TupleTableSlot *
exttable_ExecForeignInsert(EState *estate,
ResultRelInfo *rinfo,
TupleTableSlot *slot,
TupleTableSlot *planSlot)
{
ExternalInsertDescData *extInsertDesc;
/* Open the external resouce on first call. */
extInsertDesc = (ExternalInsertDescData *) rinfo->ri_FdwState;
if (!extInsertDesc)
{
extInsertDesc = external_insert_init(rinfo->ri_RelationDesc);
rinfo->ri_FdwState = extInsertDesc;
}
(void) external_insert(extInsertDesc, slot);
return slot;
}
static void
exttable_EndForeignModify(EState *estate, ResultRelInfo *rinfo)
{
ExternalInsertDescData *extInsertDesc = (ExternalInsertDescData *) rinfo->ri_FdwState;
if (extInsertDesc == NULL)
return;
external_insert_finish(extInsertDesc);
}
static void exttable_BeginForeignInsert(ModifyTableState *mtstate,
ResultRelInfo *resultRelInfo)
{
/*
* This would be the natural place to call external_insert_init(), but we
* delay that until the first actual insert. That's because we don't want
* to open the external resource if we don't end up actually inserting any
* rows in this segment. In particular, we don't want to initialize the
* external resource in the QD node, when all the actual insertions happen
* in the segments.
*/
}
static void exttable_EndForeignInsert(EState *estate,
ResultRelInfo *resultRelInfo)
{
ExternalInsertDescData *extInsertDesc = (ExternalInsertDescData *) resultRelInfo->ri_FdwState;
if (extInsertDesc == NULL)
return;
external_insert_finish(extInsertDesc);
}
Datum
gp_exttable_fdw_handler(PG_FUNCTION_ARGS)
{
FdwRoutine *routine = makeNode(FdwRoutine);
routine->GetForeignRelSize = exttable_GetForeignRelSize;
routine->GetForeignPaths = exttable_GetForeignPaths;
routine->GetForeignPlan = exttable_GetForeignPlan;
routine->BeginForeignScan = exttable_BeginForeignScan;
routine->IterateForeignScan = exttable_IterateForeignScan;
routine->ReScanForeignScan = exttable_ReScanForeignScan;
routine->EndForeignScan = exttable_EndForeignScan;
routine->IsForeignRelUpdatable = exttable_IsForeignRelUpdatable;
routine->BeginForeignModify = exttable_BeginForeignModify;
routine->ExecForeignInsert = exttable_ExecForeignInsert;
routine->EndForeignModify = exttable_EndForeignModify;
routine->BeginForeignInsert = exttable_BeginForeignInsert;
routine->EndForeignInsert = exttable_EndForeignInsert;
PG_RETURN_POINTER(routine);
};
/*
* cost_externalscan
* Determines and returns the cost of scanning an external relation.
*
* Right now this is not very meaningful at all but we'll probably
* want to make some good estimates in the future.
*/
static void
cost_externalscan(ForeignPath *path, PlannerInfo *root,
RelOptInfo *baserel, ParamPathInfo *param_info)
{
Cost startup_cost = 0;
Cost run_cost = 0;
Cost cpu_per_tuple;
/* Should only be applied to external relations */
Assert(baserel->relid > 0);
Assert(baserel->rtekind == RTE_RELATION);
/* Mark the path with the correct row estimate */
if (param_info)
path->path.rows = param_info->ppi_rows;
else
path->path.rows = baserel->rows;
/*
* disk costs
*/
run_cost += seq_page_cost * baserel->pages;
/* CPU costs */
startup_cost += baserel->baserestrictcost.startup;
cpu_per_tuple = cpu_tuple_cost + baserel->baserestrictcost.per_tuple;
run_cost += cpu_per_tuple * baserel->tuples;
path->path.startup_cost = startup_cost;
path->path.total_cost = startup_cost + run_cost;
}
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