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cassandra2_fdw.c
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cassandra2_fdw.c
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/*-------------------------------------------------------------------------
*
* Cassandra2 Foreign Data Wrapper for PostgreSQL
*
* Copyright (c) 2015 Jaimin Pan
*
* This software is released under the PostgreSQL Licence
*
* Author: Jaimin Pan <[email protected]>
*
* IDENTIFICATION
* cassandra2_fdw/cassandra2_fdw.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#if (PG_VERSION_NUM < 100000)
#error Oldest supported PostgreSQL version is 10 (100000)
#endif /* PG_VERSION_NUM < 100000 */
#include <cassandra.h>
#include "cassandra2_fdw.h"
#include "access/htup_details.h"
#include "access/reloptions.h"
#include "access/sysattr.h"
#include "executor/spi.h"
#include "foreign/fdwapi.h"
#include "common/md5.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "mb/pg_wchar.h"
#include "optimizer/cost.h"
#include "optimizer/restrictinfo.h"
#include "catalog/pg_foreign_server.h"
#include "catalog/pg_foreign_table.h"
#include "catalog/pg_user_mapping.h"
#include "catalog/pg_type.h"
#include "commands/defrem.h"
#include "commands/explain.h"
#include "commands/vacuum.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/pathnode.h"
#if PG_VERSION_NUM >= 130000
#include "optimizer/paths.h"
#endif /* PG_VERSION_NUM 130000 */
#include "optimizer/planmain.h"
#include "optimizer/restrictinfo.h"
#if PG_VERSION_NUM < 120000
#include "nodes/relation.h"
#include "optimizer/var.h"
#include "utils/tqual.h"
#else
#include "nodes/pathnodes.h"
#include "optimizer/optimizer.h"
#include "access/heapam.h"
#endif /* PG_VERSION_NUM 120000 */
#include "optimizer/paths.h"
#include "parser/parsetree.h"
#include "storage/fd.h"
#include "storage/ipc.h"
#include "utils/acl.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/guc.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
/* defined in backend/commands/analyze.c */
#ifndef WIDTH_THRESHOLD
#define WIDTH_THRESHOLD 1024
#endif /* WIDTH_THRESHOLD */
#if PG_VERSION_NUM >= 90500
#define IMPORT_API
/* array_create_iterator has a new signature from 9.5 on */
#define array_create_iterator(arr, slice_ndim) array_create_iterator(arr, slice_ndim, NULL)
#else
#undef IMPORT_API
#endif /* PG_VERSION_NUM */
#if PG_VERSION_NUM >= 90600
#define JOIN_API
/* the useful macro IS_SIMPLE_REL is defined in v10, backport */
#ifndef IS_SIMPLE_REL
#define IS_SIMPLE_REL(rel) \
((rel)->reloptkind == RELOPT_BASEREL || \
(rel)->reloptkind == RELOPT_OTHER_MEMBER_REL)
#endif
#if (PG_VERSION_NUM < 110000)
#define TupleDescAttr(tupdesc, i) ((tupdesc)->attrs[(i)])
#else
#define get_relid_attribute_name(relid, varattno) get_attname((relid), (varattno), false)
#endif
/* GetConfigOptionByName has a new signature from 9.6 on */
#define GetConfigOptionByName(name, varname) GetConfigOptionByName(name, varname, false)
#else
#undef JOIN_API
#endif /* PG_VERSION_NUM */
#if PG_VERSION_NUM < 110000
/* backport macro from V11 */
#define TupleDescAttr(tupdesc, i) ((tupdesc)->attrs[(i)])
#endif /* PG_VERSION_NUM */
/* list API has changed in v13 */
#if PG_VERSION_NUM < 130000
#define list_next(l, e) lnext((e))
#define do_each_cell(cell, list, element) for_each_cell(cell, (element))
#else
#define list_next(l, e) lnext((l), (e))
#define do_each_cell(cell, list, element) for_each_cell(cell, (list), (element))
#endif /* PG_VERSION_NUM */
/* "table_open" was "heap_open" before v12 */
#if PG_VERSION_NUM < 120000
#define table_open(x, y) heap_open(x, y)
#define table_close(x, y) heap_close(x, y)
#endif /* PG_VERSION_NUM */
PG_MODULE_MAGIC;
/* 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
/*
* Describes the valid options for objects that use this wrapper.
*/
struct CassFdwOption
{
const char *optname;
Oid optcontext; /* Oid of catalog in which option may appear */
};
/*
* Valid options for cassandra2_fdw.
*/
static struct CassFdwOption valid_options[] =
{
/* Connection options */
{ "host", ForeignServerRelationId },
{ "port", ForeignServerRelationId },
{ "protocol", ForeignServerRelationId },
{ "username", UserMappingRelationId },
{ "password", UserMappingRelationId },
{ "query", ForeignTableRelationId },
{ "schema_name", ForeignTableRelationId },
{ "table_name", ForeignTableRelationId },
/* Sentinel */
{ NULL, InvalidOid }
};
/*
* FDW-specific information for RelOptInfo.fdw_private.
*/
typedef struct CassFdwPlanState
{
/* 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;
/* Estimated size and cost for a scan with baserestrictinfo quals. */
double rows;
int width;
Cost startup_cost;
Cost total_cost;
} CassFdwPlanState;
/*
* FDW-specific information for ForeignScanState.fdw_state.
*/
typedef struct CassFdwScanState
{
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 */
int NumberOfColumns;
/* for remote query execution */
CassSession *cass_conn; /* connection for the scan */
bool sql_sended;
CassStatement *statement;
/* 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 */
/* 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 */
/* working memory contexts */
MemoryContext batch_cxt; /* context holding current batch of tuples */
MemoryContext temp_cxt; /* context for per-tuple temporary data */
} CassFdwScanState;
enum CassFdwScanPrivateIndex
{
/* SQL statement to execute remotely (as a String node) */
CassFdwScanPrivateSelectSql,
/* Integer list of attribute numbers retrieved by the SELECT */
CassFdwScanPrivateRetrievedAttrs
};
/*
* SQL functions
*/
extern Datum cassandra2_fdw_handler(PG_FUNCTION_ARGS);
extern Datum cassandra2_fdw_validator(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(cassandra2_fdw_handler);
PG_FUNCTION_INFO_V1(cassandra2_fdw_validator);
/*
* FDW callback routines
*/
static void cassGetForeignRelSize(PlannerInfo *root, RelOptInfo *baserel, Oid foreigntableid);
static void cassGetForeignPaths(PlannerInfo *root, RelOptInfo *baserel, Oid foreigntableid);
static ForeignScan *cassGetForeignPlan(
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 cassExplainForeignScan(ForeignScanState *node, ExplainState *es);
static void cassBeginForeignScan(ForeignScanState *node, int eflags);
static TupleTableSlot *cassIterateForeignScan(ForeignScanState *node);
static void cassReScanForeignScan(ForeignScanState *node);
static void cassEndForeignScan(ForeignScanState *node);
/*
* 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 bool cassIsValidOption(const char *option, Oid context);
static void cassGetOptions(Oid foreigntableid,
char **host, int *port,
char **username, char **password,
char **query, char **tablename);
static void create_cursor(ForeignScanState *node);
static void close_cursor(CassFdwScanState *fsstate);
static void fetch_more_data(ForeignScanState *node);
static void pgcass_transferValue(StringInfo buf, const CassValue* value);
static HeapTuple make_tuple_from_result_row(const CassRow* row,
int ncolumn,
Relation rel,
AttInMetadata *attinmeta,
List *retrieved_attrs,
MemoryContext temp_context);
static void classifyConditions(PlannerInfo *root,
RelOptInfo *baserel,
List *input_conds,
List **remote_conds,
List **local_conds);
static void
deparseSelectSql(StringInfo buf,
PlannerInfo *root,
RelOptInfo *baserel,
Bitmapset *attrs_used,
List **retrieved_attrs);
/*
* Foreign-data wrapper handler function: return a struct with pointers
* to my callback routines.
*/
Datum
cassandra2_fdw_handler(PG_FUNCTION_ARGS)
{
FdwRoutine *fdwroutine = makeNode(FdwRoutine);
fdwroutine->GetForeignRelSize = cassGetForeignRelSize;
fdwroutine->GetForeignPaths = cassGetForeignPaths;
fdwroutine->GetForeignPlan = cassGetForeignPlan;
fdwroutine->ExplainForeignScan = cassExplainForeignScan;
fdwroutine->BeginForeignScan = cassBeginForeignScan;
fdwroutine->IterateForeignScan = cassIterateForeignScan;
fdwroutine->ReScanForeignScan = cassReScanForeignScan;
fdwroutine->EndForeignScan = cassEndForeignScan;
fdwroutine->AnalyzeForeignTable = NULL;
PG_RETURN_POINTER(fdwroutine);
}
/*
* Validate the generic options given to a FOREIGN DATA WRAPPER, SERVER,
* USER MAPPING or FOREIGN TABLE that uses file_fdw.
*
* Raise an ERROR if the option or its value is considered invalid.
*/
Datum
cassandra2_fdw_validator(PG_FUNCTION_ARGS)
{
List *options_list = untransformRelOptions(PG_GETARG_DATUM(0));
Oid catalog = PG_GETARG_OID(1);
char *svr_host = NULL;
int svr_port = 0;
char *svr_username = NULL;
char *svr_password = NULL;
char *svr_query = NULL;
char *svr_schema = NULL;
char *svr_table = NULL;
ListCell *cell;
/*
* Check that only options supported by cassandra2_fdw,
* and allowed for the current object type, are given.
*/
foreach(cell, options_list)
{
DefElem *def = (DefElem *) lfirst(cell);
if (!cassIsValidOption(def->defname, catalog))
{
const struct CassFdwOption *opt;
StringInfoData buf;
/*
* Unknown option specified, complain about it. Provide a hint
* with list of valid options for the object.
*/
initStringInfo(&buf);
for (opt = valid_options; opt->optname; opt++)
{
if (catalog == opt->optcontext)
appendStringInfo(&buf, "%s%s", (buf.len > 0) ? ", " : "",
opt->optname);
}
ereport(ERROR,
(errcode(ERRCODE_FDW_INVALID_OPTION_NAME),
errmsg("invalid option \"%s\"", def->defname),
buf.len > 0
? errhint("Valid options in this context are: %s",
buf.data)
: errhint("There are no valid options in this context.")));
}
if (strcmp(def->defname, "host") == 0)
{
if (svr_host)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("conflicting or redundant options")));
svr_host = defGetString(def);
}
if (strcmp(def->defname, "port") == 0)
{
if (svr_port)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("conflicting or redundant options")));
svr_port = atoi(defGetString(def));
}
else if (strcmp(def->defname, "username") == 0)
{
if (svr_username)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("conflicting or redundant options")));
svr_username = defGetString(def);
}
else if (strcmp(def->defname, "password") == 0)
{
if (svr_password)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("conflicting or redundant options")));
svr_password = defGetString(def);
}
else if (strcmp(def->defname, "query") == 0)
{
if (svr_table)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("conflicting or redundant options: query cannot be used with table")));
if (svr_query)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("conflicting or redundant options")));
svr_query = defGetString(def);
}
else if (strcmp(def->defname, "schema_name") == 0)
{
if (svr_schema)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("conflicting or redundant options")));
svr_schema = defGetString(def);
}
else if (strcmp(def->defname, "table_name") == 0)
{
if (svr_query)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("conflicting or redundant options: table_name cannot be used with query")));
if (svr_table)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("conflicting or redundant options")));
svr_table = defGetString(def);
}
}
if (catalog == ForeignServerRelationId && svr_host == NULL)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("host must be specified")));
if (catalog == ForeignTableRelationId &&
svr_query == NULL && svr_table == NULL)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("either table_name or query must be specified")));
PG_RETURN_VOID();
}
/*
* Check if the provided option is one of the valid options.
* context is the Oid of the catalog holding the object the option is for.
*/
static bool
cassIsValidOption(const char *option, Oid context)
{
const struct CassFdwOption *opt;
for (opt = valid_options; opt->optname; opt++)
{
if (context == opt->optcontext && strcmp(opt->optname, option) == 0)
return true;
}
return false;
}
/*
* Fetch the options for a fdw foreign table.
*/
static void
cassGetOptions(Oid foreigntableid, char **host, int *port,
char **username, char **password, char **query, char **tablename)
{
ForeignTable *table;
ForeignServer *server;
UserMapping *user;
List *options;
ListCell *lc;
/*
* Extract options from FDW objects.
*/
table = GetForeignTable(foreigntableid);
server = GetForeignServer(table->serverid);
user = GetUserMapping(GetUserId(), server->serverid);
options = NIL;
options = list_concat(options, table->options);
options = list_concat(options, server->options);
options = list_concat(options, user->options);
/* Loop through the options, and get the server/port */
foreach(lc, options)
{
DefElem *def = (DefElem *) lfirst(lc);
if (strcmp(def->defname, "username") == 0)
{
*username = defGetString(def);
}
else if (strcmp(def->defname, "password") == 0)
{
*password = defGetString(def);
}
else if (strcmp(def->defname, "query") == 0)
{
*query = defGetString(def);
}
else if (strcmp(def->defname, "table_name") == 0)
{
*tablename = defGetString(def);
}
else if (strcmp(def->defname, "host") == 0)
{
*host = defGetString(def);
}
else if (strcmp(def->defname, "port") == 0)
{
*port = atoi(defGetString(def));
}
}
}
//#if (PG_VERSION_NUM >= 90200)
/*
* cassGetForeignRelSize
* Obtain relation size estimates for a foreign table
*/
static void
cassGetForeignRelSize(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid)
{
CassFdwPlanState *fpinfo;
ListCell *lc;
fpinfo = (CassFdwPlanState *) palloc0(sizeof(CassFdwPlanState));
baserel->fdw_private = (void *) fpinfo;
/*
* 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);
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);
}
//TODO
/* Fetch options */
/* Estimate relation size */
{
/*
* 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 + sizeof(HeapTupleHeaderData));
#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);
}
}
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)
{
*p_rows = baserel->rows;
#if (PG_VERSION_NUM >= 90600)
*p_width = baserel->reltarget->width;
#else
*p_width = baserel->width;
#endif
*p_startup_cost = DEFAULT_FDW_STARTUP_COST;
*p_total_cost = DEFAULT_FDW_TUPLE_COST * 100;
}
/*
* cassGetForeignPaths
* (9.2+) Get the foreign paths
*/
static void
cassGetForeignPaths(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid)
{
CassFdwPlanState *fpinfo = (CassFdwPlanState *) 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 >= 10000)
NULL,
#endif
fpinfo->rows + baserel->rows,
fpinfo->startup_cost,
fpinfo->total_cost,
NIL, /* no pathkeys */
NULL, /* no outer rel either */
#if (PG_VERSION_NUM >= 90500)
NULL, /* no fdw_outerpath */
#endif
NIL); /* no fdw_private list */
add_path(baserel, (Path *) path);
//TODO
}
/*
* cassGetForeignPlan
* Create ForeignScan plan node which implements selected best path
*/
static ForeignScan *
cassGetForeignPlan(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid,
ForeignPath *best_path,
List *tlist,
List *scan_clauses
#if (PG_VERSION_NUM >= 90500)
,
Plan *outer_plan
#endif
)
{
CassFdwPlanState *fpinfo = (CassFdwPlanState *) baserel->fdw_private;
Index scan_relid = baserel->relid;
List *fdw_private;
List *local_exprs = NIL;
StringInfoData sql;
List *retrieved_attrs;
local_exprs = extract_actual_clauses(scan_clauses, false);
/*
* 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);
/*
* Build the fdw_private list that will be available to the executor.
* Items in the list must match enum CassFdwScanPrivateIndex, 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,
NIL,
fdw_private
#if (PG_VERSION_NUM >= 90500)
,
NIL, /* no custom tlist */
NIL, /* no remote quals */
outer_plan
#endif
);
}
//#endif /* #if (PG_VERSION_NUM >= 90200) */
/*
* cassExplainForeignScan
* Produce extra output for EXPLAIN
*/
static void
cassExplainForeignScan(ForeignScanState *node, ExplainState *es)
{
List *fdw_private;
char *sql;
char *svr_host = NULL;
int svr_port = 0;
char *svr_username = NULL;
char *svr_password = NULL;
char *svr_query = NULL;
char *svr_table = NULL;
if (es->verbose)
{
/* Fetch options */
cassGetOptions(RelationGetRelid(node->ss.ss_currentRelation),
&svr_host, &svr_port,
&svr_username, &svr_password,
&svr_query, &svr_table);
fdw_private = ((ForeignScan *) node->ss.ps.plan)->fdw_private;
sql = strVal(list_nth(fdw_private, CassFdwScanPrivateSelectSql));
ExplainPropertyText("Remote SQL", sql, es);
}
}
/*
* cassBeginForeignScan
* Initiate access to the database
*/
static void
cassBeginForeignScan(ForeignScanState *node, int eflags)
{
ForeignScan *fsplan = (ForeignScan *) node->ss.ps.plan;
EState *estate = node->ss.ps.state;
CassFdwScanState *fsstate;
RangeTblEntry *rte;
Oid userid;
ForeignTable *table;
ForeignServer *server;
UserMapping *user;
/*
* 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 = (CassFdwScanState *) palloc0(sizeof(CassFdwScanState));
node->fdw_state = (void *) fsstate;
/*
* Identify which user to do the remote access as. This should match what
* ExecCheckRTEPerms() does.
*/
rte = rt_fetch(fsplan->scan.scanrelid, estate->es_range_table);
userid = rte->checkAsUser ? rte->checkAsUser : GetUserId();
/* Get info about foreign table. */
fsstate->rel = node->ss.ss_currentRelation;
table = GetForeignTable(RelationGetRelid(fsstate->rel));
server = GetForeignServer(table->serverid);
user = GetUserMapping(userid, server->serverid);
/*
* Get connection to the foreign server. Connection manager will
* establish new connection if necessary.
*/
fsstate->cass_conn = pgcass_GetConnection(server, user, false);
fsstate->sql_sended = false;
/* Get private info created by planner functions. */
fsstate->query = strVal(list_nth(fsplan->fdw_private,
CassFdwScanPrivateSelectSql));
fsstate->retrieved_attrs = (List *) list_nth(fsplan->fdw_private,
CassFdwScanPrivateRetrievedAttrs);
/* Create contexts for batches of tuples and per-tuple temp workspace. */
fsstate->batch_cxt = AllocSetContextCreate(estate->es_query_cxt,
"cassandra2_fdw tuple data",
ALLOCSET_DEFAULT_MINSIZE,
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
fsstate->temp_cxt = AllocSetContextCreate(estate->es_query_cxt,
"cassandra2_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));
}
/*
* cassIterateForeignScan
* Read next record from the data file and store it into the
* ScanTupleSlot as a virtual tuple
*/
static TupleTableSlot*
cassIterateForeignScan(ForeignScanState *node)
{
CassFdwScanState *fsstate = (CassFdwScanState *) node->fdw_state;
TupleTableSlot *slot = node->ss.ss_ScanTupleSlot;
/*
* If this is the first call after Begin or ReScan, we need to create the
* cursor on the remote side.
*/
if (!fsstate->sql_sended)
create_cursor(node);
/*
* Get some more tuples, if we've run out.
*/
if (fsstate->next_tuple >= fsstate->num_tuples)
{
/* No point in another fetch if we already detected EOF, though. */
if (!fsstate->eof_reached)
fetch_more_data(node);
/* If we didn't get any tuples, must be end of data. */
if (fsstate->next_tuple >= fsstate->num_tuples)
return ExecClearTuple(slot);
}
/*
* Return the next tuple.
*/
#if (PG_VERSION_NUM < 120000)
ExecStoreTuple(fsstate->tuples[fsstate->next_tuple++],
slot,
InvalidBuffer,
false);
#else
ExecStoreHeapTuple(fsstate->tuples[fsstate->next_tuple++],
slot,
false);
#endif
return slot;
}
/*
* cassReScanForeignScan
* Rescan table, possibly with new parameters
*/
static void
cassReScanForeignScan(ForeignScanState *node)
{
CassFdwScanState *fsstate = (CassFdwScanState *) node->fdw_state;
/* If we haven't created the cursor yet, nothing to do. */
if (!fsstate->sql_sended)
return;
{
/* Easy: just rescan what we already have in memory, if anything */
fsstate->next_tuple = 0;
return;
}
/* 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;
}
/*
* cassEndForeignScan
* Finish scanning foreign table and dispose objects used for this scan
*/
static void
cassEndForeignScan(ForeignScanState *node)
{
CassFdwScanState *fsstate = (CassFdwScanState *) node->fdw_state;
/* if fsstate is NULL, we are in EXPLAIN; nothing to do */
if (fsstate == NULL)
return;
/* Close the cursor if open, to prevent accumulation of cursors */
if (fsstate->sql_sended)
close_cursor(fsstate);
/* Release remote connection */
pgcass_ReleaseConnection(fsstate->cass_conn);
fsstate->cass_conn = NULL;
/* MemoryContexts will be deleted automatically. */
}
/*
* Create cursor for node's query with current parameter values.
*/
static void
create_cursor(ForeignScanState *node)
{
CassFdwScanState *fsstate = (CassFdwScanState *) node->fdw_state;
/* Build statement and execute query */
fsstate->statement = cass_statement_new(fsstate->query, 0);
/* Mark the cursor as created, and show no tuples have been retrieved */
fsstate->sql_sended = true;
fsstate->tuples = NULL;
fsstate->num_tuples = 0;
fsstate->next_tuple = 0;
fsstate->fetch_ct_2 = 0;
fsstate->eof_reached = false;
}
/*
* Utility routine to close a cursor.
*/
static void
close_cursor(CassFdwScanState *fsstate)
{
if (fsstate->statement)
cass_statement_free(fsstate->statement);
}
/*
* Fetch some more rows from the node's cursor.
*/
static void
fetch_more_data(ForeignScanState *node)
{
CassFdwScanState *fsstate = (CassFdwScanState *) node->fdw_state;
/*
* We'll store the tuples in the batch_cxt. First, flush the previous
* batch.
*/
fsstate->tuples = NULL;
MemoryContextReset(fsstate->batch_cxt);
MemoryContextSwitchTo(fsstate->batch_cxt);
{
CassFuture* result_future = cass_session_execute(fsstate->cass_conn, fsstate->statement);
if (cass_future_error_code(result_future) == CASS_OK)
{
const CassResult* res;
int numrows;
CassIterator* rows;
int k;
/* Retrieve result set and iterate over the rows */
res = cass_future_get_result(result_future);
/* Stash away the state info we have already */
fsstate->NumberOfColumns = cass_result_column_count(res);
/* Convert the data into HeapTuples */
numrows = cass_result_row_count(res);
fsstate->tuples = (HeapTuple *) palloc0(numrows * sizeof(HeapTuple));
fsstate->num_tuples = numrows;
fsstate->next_tuple = 0;