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treasuredata_fdw.c
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treasuredata_fdw.c
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/*-------------------------------------------------------------------------
*
* treasuredata_fdw.c
* Foreign-data wrapper for Treasure Data
*
* Portions Copyright (c) 2016, Mitsunori Komatsu
*
* IDENTIFICATION
* treasuredata_fdw.c
*
*-------------------------------------------------------------------------
*/
#include <unistd.h>
#include <time.h>
#include "postgres.h"
#include "treasuredata_fdw.h"
#include "bridge.h"
#include "access/htup_details.h"
#include "access/sysattr.h"
#include "commands/defrem.h"
#include "commands/explain.h"
#include "commands/vacuum.h"
#include "foreign/fdwapi.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/cost.h"
#include "optimizer/pathnode.h"
#include "optimizer/paths.h"
#include "optimizer/planmain.h"
#include "optimizer/prep.h"
#include "optimizer/restrictinfo.h"
#include "optimizer/var.h"
#include "parser/parsetree.h"
#include "utils/builtins.h"
#include "utils/guc.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/rel.h"
PG_MODULE_MAGIC;
extern Datum treasuredata_fdw_handler(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(treasuredata_fdw_handler);
/* Default CPU cost to start up a foreign query. */
#define DEFAULT_FDW_STARTUP_COST 100.0
/* Default CPU cost to process 1 row (above and beyond cpu_tuple_cost). */
#define DEFAULT_FDW_TUPLE_COST 0.01
/*
* FDW-specific planner information kept in RelOptInfo.fdw_private for a
* foreign table. This information is collected by treasuredataGetForeignRelSize.
*/
typedef struct TdFdwRelationInfo
{
/* 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. */
Cost fdw_startup_cost;
Cost fdw_tuple_cost;
/* Cached catalog information. */
ForeignTable *table;
ForeignServer *server;
/* Query engine type */
QueryEngineType query_engine_type;
} TdFdwRelationInfo;
/*
* Indexes of FDW-private information stored in fdw_private lists.
*
* We store various information in ForeignScan.fdw_private to pass it from
* planner to executor. Currently we store:
*
* 1) SELECT statement text to be sent to the remote server
* 2) Integer list of attribute numbers retrieved by the SELECT
*
* These items are indexed with the enum FdwScanPrivateIndex, so an item
* can be fetched with list_nth(). For example, to get the SELECT statement:
* sql = strVal(list_nth(fdw_private, FdwScanPrivateSelectSql));
*/
enum FdwScanPrivateIndex
{
/* SQL statement to execute remotely (as a String node) */
FdwScanPrivateSelectSql,
/* Integer list of attribute numbers retrieved by the SELECT */
FdwScanPrivateRetrievedAttrs
};
/*
* Similarly, this enum describes what's kept in the fdw_private list for
* a ModifyTable node referencing a treasuredata_fdw foreign table. We store:
*
* 1) INSERT/UPDATE/DELETE statement text to be sent to the remote server
* 2) Integer list of target attribute numbers for INSERT/UPDATE
* (NIL for a DELETE)
* 3) Boolean flag showing if the remote query has a RETURNING clause
* 4) Integer list of attribute numbers retrieved by RETURNING, if any
*/
enum FdwModifyPrivateIndex
{
/* SQL statement to execute remotely (as a String node) */
FdwModifyPrivateUpdateSql,
/* Integer list of target attribute numbers for INSERT/UPDATE */
FdwModifyPrivateTargetAttnums,
/* has-returning flag (as an integer Value node) */
FdwModifyPrivateHasReturning,
/* Integer list of attribute numbers retrieved by RETURNING */
FdwModifyPrivateRetrievedAttrs
};
/*
* Execution state of a foreign scan using treasuredata_fdw.
*/
typedef struct TdFdwScanState
{
Relation rel; /* relcache entry for the foreign table */
AttInMetadata *attinmeta; /* attribute datatype conversion metadata */
/* extracted fdw_private data */
char *query; /* text of SELECT command */
List *retrieved_attrs; /* list of retrieved attribute numbers */
bool fetch_all_column; /* If all columns always need to be fetched (in case of 'query' option mode) */
/* for remote query execution */
void *td_client;
int numParams; /* number of parameters passed to query */
FmgrInfo *param_flinfo; /* output conversion functions for them */
List *param_exprs; /* executable expressions for param values */
const char **param_values; /* textual values of query parameters */
/* for storing result tuples */
HeapTuple *tuples; /* array of currently-retrieved tuples */
int num_tuples; /* # of tuples in array */
int next_tuple; /* index of next one to return */
#if 0
/* batch-level state, for optimizing rewinds and avoiding useless fetch */
int fetch_ct_2; /* Min(# of fetches done, 2) */
bool eof_reached; /* true if last fetch reached EOF */
#endif
/* working memory contexts */
#if 0
MemoryContext batch_cxt; /* context holding current batch of tuples */
#endif
MemoryContext temp_cxt; /* context for per-tuple temporary data */
/* Cached catalog information. */
ForeignTable *table;
} TdFdwScanState;
/*
* Execution state of a foreign insert/update/delete operation.
*/
typedef struct TdFdwModifyState
{
Relation rel; /* relcache entry for the foreign table */
AttInMetadata *attinmeta; /* attribute datatype conversion metadata */
/* for remote query execution */
void *td_client;
TdFdwOption fdw_option;
char *tmp_table_name; /* used for atomic import */
/* extracted fdw_private data */
char *query; /* text of INSERT/UPDATE/DELETE command */
List *target_attrs; /* list of target attribute numbers */
#if 0
bool has_returning; /* is there a RETURNING clause? */
List *retrieved_attrs; /* attr numbers retrieved by RETURNING */
#endif
/* attribute info */
AttrNumber ctidAttno; /* attnum of input resjunk ctid column */
int p_nums; /* number of parameters to transmit */
FmgrInfo *p_flinfo; /* output conversion functions for them */
const char **column_types;
const char **column_names;
/* working memory context */
MemoryContext temp_cxt; /* context for per-tuple temporary data */
/* Cached catalog information. */
ForeignTable *table;
} TdFdwModifyState;
#if 0
/*
* Workspace for analyzing a foreign table.
*/
typedef struct TdFdwAnalyzeState
{
Relation rel; /* relcache entry for the foreign table */
AttInMetadata *attinmeta; /* attribute datatype conversion metadata */
List *retrieved_attrs; /* attr numbers retrieved by query */
/* collected sample rows */
HeapTuple *rows; /* array of size targrows */
int targrows; /* target # of sample rows */
int numrows; /* # of sample rows collected */
/* for random sampling */
double samplerows; /* # of rows fetched */
double rowstoskip; /* # of rows to skip before next sample */
ReservoirStateData rstate; /* state for reservoir sampling */
/* working memory contexts */
MemoryContext anl_cxt; /* context for per-analyze lifespan data */
MemoryContext temp_cxt; /* context for per-tuple temporary data */
} TdFdwAnalyzeState;
#endif
/*
* Identify the attribute where data conversion fails.
*/
typedef struct ConversionLocation
{
Relation rel; /* foreign table's relcache entry */
AttrNumber cur_attno; /* attribute number being processed, or 0 */
} ConversionLocation;
/* Callback argument for ec_member_matches_foreign */
typedef struct
{
Expr *current; /* current expr, or NULL if not yet found */
List *already_used; /* expressions already dealt with */
} ec_member_foreign_arg;
/*
* FDW callback routines
*/
static void treasuredataGetForeignRelSize(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid);
static void treasuredataGetForeignPaths(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid);
static ForeignScan *treasuredataGetForeignPlan(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid,
ForeignPath *best_path,
List *tlist,
List *scan_clauses
#if PG_VERSION_NUM >= 90500
, Plan *outer_plan
#endif
);
static void treasuredataBeginForeignScan(ForeignScanState *node, int eflags);
static TupleTableSlot *treasuredataIterateForeignScan(ForeignScanState *node);
// static void treasuredataReScanForeignScan(ForeignScanState *node);
static void treasuredataEndForeignScan(ForeignScanState *node);
static void treasuredataAddForeignUpdateTargets(Query *parsetree,
RangeTblEntry *target_rte,
Relation target_relation);
static List *treasuredataPlanForeignModify(PlannerInfo *root,
ModifyTable *plan,
Index resultRelation,
int subplan_index);
static void treasuredataBeginForeignModify(ModifyTableState *mtstate,
ResultRelInfo *resultRelInfo,
List *fdw_private,
int subplan_index,
int eflags);
static TupleTableSlot *treasuredataExecForeignInsert(EState *estate,
ResultRelInfo *resultRelInfo,
TupleTableSlot *slot,
TupleTableSlot *planSlot);
static void treasuredataEndForeignModify(EState *estate,
ResultRelInfo *resultRelInfo);
#if 0
static TupleTableSlot *treasuredataExecForeignUpdate(EState *estate,
ResultRelInfo *resultRelInfo,
TupleTableSlot *slot,
TupleTableSlot *planSlot);
static TupleTableSlot *treasuredataExecForeignDelete(EState *estate,
ResultRelInfo *resultRelInfo,
TupleTableSlot *slot,
TupleTableSlot *planSlot);
static int treasuredataIsForeignRelUpdatable(Relation rel);
static void treasuredataExplainForeignScan(ForeignScanState *node,
ExplainState *es);
static void treasuredataExplainForeignModify(ModifyTableState *mtstate,
ResultRelInfo *rinfo,
List *fdw_private,
int subplan_index,
ExplainState *es);
static bool treasuredataAnalyzeForeignTable(Relation relation,
AcquireSampleRowsFunc *func,
BlockNumber *totalpages);
#endif
#if PG_VERSION_NUM >= 90500
static List *treasuredataImportForeignSchema(ImportForeignSchemaStmt *stmt,
Oid serverOid);
#endif
/*
* Helper functions
*/
static void estimate_path_cost_size(PlannerInfo *root,
RelOptInfo *baserel,
List *join_conds,
double *p_rows, int *p_width,
Cost *p_startup_cost, Cost *p_total_cost);
static const char **convert_prep_stmt_params(TdFdwModifyState *fmstate,
ItemPointer tupleid,
TupleTableSlot *slot);
#if 0
static int set_transmission_modes(void);
static void reset_transmission_modes(int nestlevel);
static bool ec_member_matches_foreign(PlannerInfo *root, RelOptInfo *rel,
EquivalenceClass *ec, EquivalenceMember *em,
void *arg);
static void fetch_more_data(ForeignScanState *node);
static void close_cursor(PGconn *conn, unsigned int cursor_number);
static void prepare_foreign_modify(TdFdwModifyState *fmstate);
static void store_returning_result(TdFdwModifyState *fmstate,
TupleTableSlot *slot, PGresult *res);
static int treasuredataAcquireSampleRowsFunc(Relation relation, int elevel,
HeapTuple *rows, int targrows,
double *totalrows,
double *totaldeadrows);
static void analyze_row_processor(PGresult *res, int row,
TdFdwAnalyzeState *astate);
#endif
static HeapTuple make_tuple_from_result_row(void *td_client,
bool fetch_all_column,
Relation rel,
AttInMetadata *attinmeta,
List *retrieved_attrs,
MemoryContext temp_context);
static void conversion_error_callback(void *arg);
/*
* Foreign-data wrapper handler function: return a struct with pointers
* to my callback routines.
*/
Datum
treasuredata_fdw_handler(PG_FUNCTION_ARGS)
{
FdwRoutine *routine = makeNode(FdwRoutine);
/* Functions for scanning foreign tables */
routine->GetForeignRelSize = treasuredataGetForeignRelSize;
routine->GetForeignPaths = treasuredataGetForeignPaths;
routine->GetForeignPlan = treasuredataGetForeignPlan;
routine->BeginForeignScan = treasuredataBeginForeignScan;
routine->IterateForeignScan = treasuredataIterateForeignScan;
// routine->ReScanForeignScan = treasuredataReScanForeignScan;
routine->EndForeignScan = treasuredataEndForeignScan;
/* Functions for updating foreign tables */
routine->AddForeignUpdateTargets = treasuredataAddForeignUpdateTargets;
routine->PlanForeignModify = treasuredataPlanForeignModify;
routine->BeginForeignModify = treasuredataBeginForeignModify;
routine->ExecForeignInsert = treasuredataExecForeignInsert;
routine->EndForeignModify = treasuredataEndForeignModify;
#if 0
routine->ExecForeignUpdate = treasuredataExecForeignUpdate;
routine->ExecForeignDelete = treasuredataExecForeignDelete;
routine->IsForeignRelUpdatable = treasuredataIsForeignRelUpdatable;
/* Support functions for EXPLAIN */
routine->ExplainForeignScan = treasuredataExplainForeignScan;
routine->ExplainForeignModify = treasuredataExplainForeignModify;
/* Support functions for ANALYZE */
routine->AnalyzeForeignTable = treasuredataAnalyzeForeignTable;
#endif
#if PG_VERSION_NUM >= 90500
/* Support functions for IMPORT FOREIGN SCHEMA */
routine->ImportForeignSchema = treasuredataImportForeignSchema;
#endif
PG_RETURN_POINTER(routine);
}
/*
* treasuredataGetForeignRelSize
* Estimate # of rows and width of the result of the scan
*
* We should consider the effect of all baserestrictinfo clauses here, but
* not any join clauses.
*/
static void
treasuredataGetForeignRelSize(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid)
{
TdFdwRelationInfo *fpinfo;
ListCell *lc;
/*
* We use TdFdwRelationInfo to pass various information to subsequent
* functions.
*/
fpinfo = (TdFdwRelationInfo *) palloc0(sizeof(TdFdwRelationInfo));
baserel->fdw_private = (void *) fpinfo;
/* Look up foreign-table catalog info. */
fpinfo->table = GetForeignTable(foreigntableid);
fpinfo->server = GetForeignServer(fpinfo->table->serverid);
{
TdFdwOption fdw_option;
ExtractFdwOptions(fpinfo->table, &fdw_option);
if (strcmp(fdw_option.query_engine, "presto") == 0)
fpinfo->query_engine_type = QUERY_ENGINE_PRESTO;
else
fpinfo->query_engine_type = QUERY_ENGINE_HIVE;
}
fpinfo->fdw_startup_cost = DEFAULT_FDW_STARTUP_COST;
fpinfo->fdw_tuple_cost = DEFAULT_FDW_TUPLE_COST;
/*
* Identify which baserestrictinfo clauses can be sent to the remote
* server and which can't.
*/
classifyConditions(root, baserel, baserel->baserestrictinfo,
&fpinfo->remote_conds, &fpinfo->local_conds);
/*
* Identify which attributes will need to be retrieved from the remote
* server. These include all attrs needed for joins or final output, plus
* all attrs used in the local_conds. (Note: if we end up using a
* parameterized scan, it's possible that some of the join clauses will be
* sent to the remote and thus we wouldn't really need to retrieve the
* columns used in them. Doesn't seem worth detecting that case though.)
*/
fpinfo->attrs_used = NULL;
#if PG_VERSION_NUM >= 90600
pull_varattnos((Node *) baserel->reltarget->exprs, baserel->relid,
&fpinfo->attrs_used);
#else
pull_varattnos((Node *) baserel->reltargetlist, baserel->relid,
&fpinfo->attrs_used);
#endif
foreach(lc, fpinfo->local_conds)
{
RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
pull_varattnos((Node *) rinfo->clause, baserel->relid,
&fpinfo->attrs_used);
}
/*
* Compute the selectivity and cost of the local_conds, so we don't have
* to do it over again for each path. The best we can do for these
* conditions is to estimate selectivity on the basis of local statistics.
*/
fpinfo->local_conds_sel = clauselist_selectivity(root,
fpinfo->local_conds,
baserel->relid,
JOIN_INNER,
NULL);
cost_qual_eval(&fpinfo->local_conds_cost, fpinfo->local_conds, root);
/*
* Estimate using whatever statistics we have locally, in a way similar
* to ordinary tables.
*
* If the foreign table has never been ANALYZEd, it will have relpages
* and reltuples equal to zero, which most likely has nothing to do
* with reality. We can't do a whole lot about that if we're not
* allowed to consult the remote server, but we can use a hack similar
* to plancat.c's treatment of empty relations: use a minimum size
* estimate of 10 pages, and divide by the column-datatype-based width
* estimate to get the corresponding number of tuples.
*/
if (baserel->pages == 0 && baserel->tuples == 0)
{
baserel->pages = 10;
baserel->tuples =
#if PG_VERSION_NUM >= 90600
(10 * BLCKSZ) / (baserel->reltarget->width + MAXALIGN(SizeofHeapTupleHeader));
#elif PG_VERSION_NUM >= 90500
(10 * BLCKSZ) / (baserel->width + MAXALIGN(SizeofHeapTupleHeader));
#else
(10 * BLCKSZ) / (baserel->width + sizeof(HeapTupleHeaderData));
#endif
}
/* Estimate baserel size as best we can with local statistics. */
set_baserel_size_estimates(root, baserel);
/* Fill in basically-bogus cost estimates for use later. */
estimate_path_cost_size(root, baserel, NIL,
&fpinfo->rows, &fpinfo->width,
&fpinfo->startup_cost, &fpinfo->total_cost);
}
/*
* treasuredataGetForeignPaths
* Create possible scan paths for a scan on the foreign table
*/
static void
treasuredataGetForeignPaths(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid)
{
TdFdwRelationInfo *fpinfo = (TdFdwRelationInfo *) baserel->fdw_private;
ForeignPath *path;
/*
* Create simplest ForeignScan path node and add it to baserel. This path
* corresponds to SeqScan path of regular tables (though depending on what
* baserestrict conditions we were able to send to remote, there might
* actually be an indexscan happening there). We already did all the work
* to estimate cost and size of this path.
*/
path = create_foreignscan_path(root, baserel,
#if PG_VERSION_NUM >= 90600
NULL, /* default pathtarget */
#endif
fpinfo->rows,
fpinfo->startup_cost,
fpinfo->total_cost,
NIL, /* no pathkeys */
NULL, /* no outer rel either */
#if PG_VERSION_NUM >= 90500
NULL, /* no extra plan */
#endif
NIL); /* no fdw_private list */
add_path(baserel, (Path *) path);
}
/*
* treasuredataGetForeignPlan
* Create ForeignScan plan node which implements selected best path
*/
static ForeignScan *
treasuredataGetForeignPlan(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid,
ForeignPath *best_path,
List *tlist,
List *scan_clauses
#if PG_VERSION_NUM >= 90500
, Plan *outer_plan
#endif
)
{
TdFdwRelationInfo *fpinfo = (TdFdwRelationInfo *) baserel->fdw_private;
Index scan_relid = baserel->relid;
List *fdw_private;
List *remote_conds = NIL;
List *remote_exprs = NIL;
List *local_exprs = NIL;
List *params_list = NIL;
List *retrieved_attrs;
TdFdwOption fdw_option;
StringInfoData sql;
ListCell *lc;
ExtractFdwOptions(fpinfo->table, &fdw_option);
/*
* Separate the scan_clauses into those that can be executed remotely and
* those that can't. baserestrictinfo clauses that were previously
* determined to be safe or unsafe by classifyConditions are shown in
* fpinfo->remote_conds and fpinfo->local_conds. Anything else in the
* scan_clauses list will be a join clause, which we have to check for
* remote-safety.
*
* Note: the join clauses we see here should be the exact same ones
* previously examined by treasuredataGetForeignPaths. Possibly it'd be worth
* passing forward the classification work done then, rather than
* repeating it here.
*
* This code must match "extract_actual_clauses(scan_clauses, false)"
* except for the additional decision about remote versus local execution.
* Note however that we don't strip the RestrictInfo nodes from the
* remote_conds list, since appendWhereClause expects a list of
* RestrictInfos.
*/
foreach(lc, scan_clauses)
{
RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
Assert(IsA(rinfo, RestrictInfo));
/* Ignore any pseudoconstants, they're dealt with elsewhere */
if (rinfo->pseudoconstant)
continue;
if (list_member_ptr(fpinfo->remote_conds, rinfo))
{
remote_conds = lappend(remote_conds, rinfo);
remote_exprs = lappend(remote_exprs, rinfo->clause);
}
else if (list_member_ptr(fpinfo->local_conds, rinfo))
local_exprs = lappend(local_exprs, rinfo->clause);
else if (is_foreign_expr(root, baserel, rinfo->clause))
{
remote_conds = lappend(remote_conds, rinfo);
remote_exprs = lappend(remote_exprs, rinfo->clause);
}
else
local_exprs = lappend(local_exprs, rinfo->clause);
}
/*
* Build the query string to be sent for execution, and identify
* expressions to be sent as parameters.
*/
initStringInfo(&sql);
deparseSelectSql(&sql, root, baserel, fpinfo->attrs_used,
&retrieved_attrs, fpinfo->query_engine_type);
/* Use a SQL specified as 'query' option param instead if it's enabled */
if (fdw_option.query != NULL)
{
initStringInfo(&sql);
appendStringInfoString(&sql, "SELECT * FROM ( ");
appendStringInfoString(&sql, fdw_option.query);
appendStringInfoString(&sql, " ) result ");
}
if (remote_conds)
appendWhereClause(&sql, root, baserel, remote_conds,
true, ¶ms_list, fpinfo->query_engine_type);
/*
* Add FOR UPDATE/SHARE if appropriate. We apply locking during the
* initial row fetch, rather than later on as is done for local tables.
* The extra roundtrips involved in trying to duplicate the local
* semantics exactly don't seem worthwhile (see also comments for
* RowMarkType).
*
* Note: because we actually run the query as a cursor, this assumes that
* DECLARE CURSOR ... FOR UPDATE is supported, which it isn't before 8.3.
*/
if (baserel->relid == root->parse->resultRelation &&
(root->parse->commandType == CMD_UPDATE ||
root->parse->commandType == CMD_DELETE))
{
elog(ERROR, "SELECT FOR UPDATE isn't supported");
}
#if PG_VERSION_NUM >= 90500
else
{
PlanRowMark *rc = get_plan_rowmark(root->rowMarks, baserel->relid);
if (rc)
{
/*
* Relation is specified as a FOR UPDATE/SHARE target, so handle
* that. (But we could also see LCS_NONE, meaning this isn't a
* target relation after all.)
*
* For now, just ignore any [NO] KEY specification, since (a) it's
* not clear what that means for a remote table that we don't have
* complete information about, and (b) it wouldn't work anyway on
* older remote servers. Likewise, we don't worry about NOWAIT.
*/
switch (rc->strength)
{
case LCS_NONE:
/* No locking needed */
break;
case LCS_FORKEYSHARE:
case LCS_FORSHARE:
elog(ERROR, "SELECT FOR SHARE isn't supported");
break;
case LCS_FORNOKEYUPDATE:
case LCS_FORUPDATE:
elog(ERROR, "SELECT FOR UPDATE isn't supported");
break;
}
}
}
#endif
/*
* Build the fdw_private list that will be available to the executor.
* Items in the list must match enum FdwScanPrivateIndex, above.
*/
fdw_private = list_make2(makeString(sql.data),
retrieved_attrs);
/*
* Create the ForeignScan node from target list, local filtering
* expressions, remote parameter expressions, and FDW private information.
*
* Note that the remote parameter expressions are stored in the fdw_exprs
* field of the finished plan node; we can't keep them in private state
* because then they wouldn't be subject to later planner processing.
*/
return make_foreignscan(tlist
, local_exprs
, scan_relid
, params_list
, fdw_private
#if PG_VERSION_NUM >= 90500
, NIL /* no custom tlist */
, remote_exprs
, outer_plan
#endif
);
}
/*
* treasuredataBeginForeignScan
* Initiate an executor scan of a foreign PostgreSQL table.
*/
static void
treasuredataBeginForeignScan(ForeignScanState *node, int eflags)
{
ForeignScan *fsplan = (ForeignScan *) node->ss.ps.plan;
EState *estate = node->ss.ps.state;
TdFdwScanState *fsstate;
int numParams;
int i;
ListCell *lc;
/*
* Do nothing in EXPLAIN (no ANALYZE) case. node->fdw_state stays NULL.
*/
if (eflags & EXEC_FLAG_EXPLAIN_ONLY)
return;
/*
* We'll save private state in node->fdw_state.
*/
fsstate = (TdFdwScanState *) palloc0(sizeof(TdFdwScanState));
node->fdw_state = (void *) fsstate;
/* Get info about foreign table. */
fsstate->rel = node->ss.ss_currentRelation;
fsstate->td_client = NULL;
/* Get private info created by planner functions. */
fsstate->query = strVal(list_nth(fsplan->fdw_private,
FdwScanPrivateSelectSql));
fsstate->retrieved_attrs = (List *) list_nth(fsplan->fdw_private,
FdwScanPrivateRetrievedAttrs);
/* Get info about foreign table. */
fsstate->table = GetForeignTable(RelationGetRelid(node->ss.ss_currentRelation));
/* Create contexts for batches of tuples and per-tuple temp workspace. */
#if 0
fsstate->batch_cxt = AllocSetContextCreate(estate->es_query_cxt,
"treasuredata_fdw tuple data",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
#endif
fsstate->temp_cxt = AllocSetContextCreate(estate->es_query_cxt,
"treasuredata_fdw temporary data",
ALLOCSET_SMALL_MINSIZE,
ALLOCSET_SMALL_INITSIZE,
ALLOCSET_SMALL_MAXSIZE);
/* Get info we'll need for input data conversion. */
fsstate->attinmeta = TupleDescGetAttInMetadata(RelationGetDescr(fsstate->rel));
/* Prepare for output conversion of parameters used in remote query. */
numParams = list_length(fsplan->fdw_exprs);
fsstate->numParams = numParams;
fsstate->param_flinfo = (FmgrInfo *) palloc0(sizeof(FmgrInfo) * numParams);
i = 0;
foreach(lc, fsplan->fdw_exprs)
{
Node *param_expr = (Node *) lfirst(lc);
Oid typefnoid;
bool isvarlena;
getTypeOutputInfo(exprType(param_expr), &typefnoid, &isvarlena);
fmgr_info(typefnoid, &fsstate->param_flinfo[i]);
i++;
}
/*
* Prepare remote-parameter expressions for evaluation. (Note: in
* practice, we expect that all these expressions will be just Params, so
* we could possibly do something more efficient than using the full
* expression-eval machinery for this. But probably there would be little
* benefit, and it'd require treasuredata_fdw to know more than is desirable
* about Param evaluation.)
*/
fsstate->param_exprs = (List *)
ExecInitExpr((Expr *) fsplan->fdw_exprs,
(PlanState *) node);
/*
* Allocate buffer for text form of query parameters, if any.
*/
if (numParams > 0)
fsstate->param_values = (const char **) palloc0(numParams * sizeof(char *));
else
fsstate->param_values = NULL;
}
/*
* treasuredataIterateForeignScan
* Retrieve next row from the result set, or clear tuple slot to indicate
* EOF.
*/
static TupleTableSlot *
treasuredataIterateForeignScan(ForeignScanState *node)
{
TdFdwScanState *fsstate = (TdFdwScanState *) node->fdw_state;
TupleTableSlot *slot = node->ss.ss_ScanTupleSlot;
HeapTuple tuple;;
if (fsstate->td_client == NULL)
{
TdFdwOption fdw_option;
ExtractFdwOptions(fsstate->table, &fdw_option);
fsstate->fetch_all_column = fdw_option.query != NULL;
fsstate->td_client = issueQuery(
fdw_option.apikey,
fdw_option.endpoint,
fdw_option.query_engine,
fdw_option.database,
fsstate->query,
fdw_option.query_download_dir);
}
tuple = make_tuple_from_result_row(
fsstate->td_client,
fsstate->fetch_all_column,
fsstate->rel,
fsstate->attinmeta,
fsstate->retrieved_attrs,
fsstate->temp_cxt);
if (tuple == NULL)
{
return ExecClearTuple(slot);
}
/*
* Return the next tuple.
*/
ExecStoreTuple(tuple, slot, InvalidBuffer, false);
return slot;
}
#if 0
/*
* treasuredataReScanForeignScan
* Restart the scan.
*/
static void
treasuredataReScanForeignScan(ForeignScanState *node)
{
TdFdwScanState *fsstate = (TdFdwScanState *) node->fdw_state;
char sql[64];
PGresult *res;
/* If we haven't created the cursor yet, nothing to do. */
if (!fsstate->cursor_exists)
return;
/*
* If any internal parameters affecting this node have changed, we'd
* better destroy and recreate the cursor. Otherwise, rewinding it should
* be good enough. If we've only fetched zero or one batch, we needn't
* even rewind the cursor, just rescan what we have.
*/
if (node->ss.ps.chgParam != NULL)
{
fsstate->cursor_exists = false;
snprintf(sql, sizeof(sql), "CLOSE c%u",
fsstate->cursor_number);
}
else if (fsstate->fetch_ct_2 > 1)
{
snprintf(sql, sizeof(sql), "MOVE BACKWARD ALL IN c%u",
fsstate->cursor_number);
}
else
{
/* Easy: just rescan what we already have in memory, if anything */
fsstate->next_tuple = 0;
return;
}
/*
* We don't use a PG_TRY block here, so be careful not to throw error
* without releasing the PGresult.
*/
res = PQexec(fsstate->conn, sql);
if (PQresultStatus(res) != PGRES_COMMAND_OK)
pgfdw_report_error(ERROR, res, fsstate->conn, true, sql);
PQclear(res);
/* Now force a fresh FETCH. */
fsstate->tuples = NULL;
fsstate->num_tuples = 0;
fsstate->next_tuple = 0;
fsstate->fetch_ct_2 = 0;
fsstate->eof_reached = false;
}
#endif
/*
* treasuredataEndForeignScan
* Finish scanning foreign table and dispose objects used for this scan
*/
static void
treasuredataEndForeignScan(ForeignScanState *node)
{
TdFdwScanState *fsstate = (TdFdwScanState *) node->fdw_state;
/* if fsstate is NULL, we are in EXPLAIN; nothing to do */
if (fsstate == NULL)
return;
releaseQueryResource(fsstate->td_client);
fsstate->td_client = NULL;
/* MemoryContexts will be deleted automatically. */
}
/*
* treasuredataAddForeignUpdateTargets
* Add resjunk column(s) needed for update/delete on a foreign table
*/
static void
treasuredataAddForeignUpdateTargets(Query *parsetree,
RangeTblEntry *target_rte,
Relation target_relation)
{
Var *var;
const char *attrname;
TargetEntry *tle;
/*
* In treasuredata_fdw, what we need is the ctid, same as for a regular table.
*/
/* Make a Var representing the desired value */
var = makeVar(parsetree->resultRelation,
SelfItemPointerAttributeNumber,
TIDOID,
-1,
InvalidOid,
0);
/* Wrap it in a resjunk TLE with the right name ... */
attrname = "ctid";
tle = makeTargetEntry((Expr *) var,
list_length(parsetree->targetList) + 1,
pstrdup(attrname),
true);
/* ... and add it to the query's targetlist */
parsetree->targetList = lappend(parsetree->targetList, tle);
}
/*
* treasuredataPlanForeignModify
* Plan an insert/update/delete operation on a foreign table
*
* Note: currently, the plan tree generated for UPDATE/DELETE will always
* include a ForeignScan that retrieves ctids (using SELECT FOR UPDATE)
* and then the ModifyTable node will have to execute individual remote
* UPDATE/DELETE commands. If there are no local conditions or joins
* needed, it'd be better to let the scan node do UPDATE/DELETE RETURNING
* and then do nothing at ModifyTable. Room for future optimization ...
*/
static List *
treasuredataPlanForeignModify(PlannerInfo *root,