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influxdb_fdw.c
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/*-------------------------------------------------------------------------
*
* InfluxDB Foreign Data Wrapper for PostgreSQL
*
* Portions Copyright (c) 2018, TOSHIBA CORPORATION
*
* IDENTIFICATION
* influxdb_fdw.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "influxdb_fdw.h"
#include <stdio.h>
#include "access/reloptions.h"
#include "access/htup_details.h"
#include "access/sysattr.h"
#include "foreign/fdwapi.h"
#include "foreign/foreign.h"
#include "optimizer/pathnode.h"
#include "optimizer/planmain.h"
#include "optimizer/cost.h"
#include "optimizer/clauses.h"
#include "optimizer/restrictinfo.h"
#include "optimizer/paths.h"
#include "optimizer/prep.h"
#include "optimizer/restrictinfo.h"
#include "optimizer/var.h"
#include "optimizer/tlist.h"
#include "funcapi.h"
#include "utils/builtins.h"
#include "utils/formatting.h"
#include "utils/rel.h"
#include "utils/lsyscache.h"
#include "utils/array.h"
#include "utils/date.h"
#include "utils/hsearch.h"
#include "utils/timestamp.h"
#include "utils/guc.h"
#include "utils/memutils.h"
#include "catalog/pg_collation.h"
#include "catalog/pg_foreign_server.h"
#include "catalog/pg_foreign_table.h"
#include "catalog/pg_user_mapping.h"
#include "catalog/pg_aggregate.h"
#include "catalog/pg_type.h"
#include "commands/defrem.h"
#include "commands/explain.h"
#include "commands/vacuum.h"
#include "storage/ipc.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "nodes/nodeFuncs.h"
#include "parser/parsetree.h"
#include "utils/typcache.h"
#include "utils/selfuncs.h"
extern PGDLLEXPORT void _PG_init(void);
bool influxdb_load_library(void);
static void influxdb_fdw_exit(int code, Datum arg);
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
/* If no remote estimates, assume a sort costs 20% extra */
#define DEFAULT_FDW_SORT_MULTIPLIER 1.2
#define IS_KEY_COLUMN(A) ((strcmp(A->defname, "key") == 0) && \
(strcmp(((Value *)(A->arg))->val.str, "true") == 0))
extern Datum influxdb_fdw_handler(PG_FUNCTION_ARGS);
extern Datum influxdb_fdw_validator(PG_FUNCTION_ARGS);
PG_FUNCTION_INFO_V1(influxdb_fdw_handler);
static void influxdbGetForeignRelSize(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid);
static void influxdbGetForeignPaths(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid);
static ForeignScan *influxdbGetForeignPlan(PlannerInfo *root,
RelOptInfo *baserel,
Oid foreigntableid,
ForeignPath *best_path,
List *tlist,
List *scan_clauses,
Plan *outer_plan);
static void influxdbBeginForeignScan(ForeignScanState *node,
int eflags);
static TupleTableSlot *influxdbIterateForeignScan(ForeignScanState *node);
static void influxdbReScanForeignScan(ForeignScanState *node);
static void influxdbEndForeignScan(ForeignScanState *node);
static void influxdbExplainForeignScan(ForeignScanState *node,
struct ExplainState *es);
static void influxdbExplainForeignModify(ModifyTableState *mtstate,
ResultRelInfo *rinfo,
List *fdw_private,
int subplan_index,
struct ExplainState *es);
static bool influxdbAnalyzeForeignTable(Relation relation,
AcquireSampleRowsFunc *func,
BlockNumber *totalpages);
static List *influxdbImportForeignSchema(ImportForeignSchemaStmt *stmt,
Oid serverOid);
static void
influxdbGetForeignUpperPaths(PlannerInfo *root,
UpperRelationKind stage,
RelOptInfo *input_rel,
RelOptInfo *output_rel
#if (PG_VERSION_NUM >= 110000)
,void *extra
#endif
);
static void influxdb_to_pg_type(StringInfo str, char *typname);
static void prepare_query_params(PlanState *node,
List *fdw_exprs,
int numParams,
FmgrInfo **param_flinfo,
List **param_exprs,
const char ***param_values,
Oid **param_types,
InfluxDBType * *param_influxdb_types,
InfluxDBValue * *param_influxdb_values);
static void process_query_params(ExprContext *econtext,
FmgrInfo *param_flinfo,
List *param_exprs,
const char **param_values,
Oid *param_types,
InfluxDBType * param_influxdb_types,
InfluxDBValue * param_influxdb_values);
static void create_cursor(ForeignScanState *node);
static bool foreign_grouping_ok(PlannerInfo *root, RelOptInfo *grouped_rel);
static void add_foreign_grouping_paths(PlannerInfo *root,
RelOptInfo *input_rel,
RelOptInfo *grouped_rel);
/*
* Library load-time initialization, sets on_proc_exit() callback for
* backend shutdown.
*/
void
_PG_init(void)
{
on_proc_exit(&influxdb_fdw_exit, PointerGetDatum(NULL));
}
/*
* influxdb_fdw_exit: Exit callback function.
*/
static void
influxdb_fdw_exit(int code, Datum arg)
{
}
Datum
influxdb_fdw_handler(PG_FUNCTION_ARGS)
{
FdwRoutine *fdwroutine = makeNode(FdwRoutine);
elog(DEBUG1, "influxdb_fdw : %s", __func__);
fdwroutine->GetForeignRelSize = influxdbGetForeignRelSize;
fdwroutine->GetForeignPaths = influxdbGetForeignPaths;
fdwroutine->GetForeignPlan = influxdbGetForeignPlan;
fdwroutine->BeginForeignScan = influxdbBeginForeignScan;
fdwroutine->IterateForeignScan = influxdbIterateForeignScan;
fdwroutine->ReScanForeignScan = influxdbReScanForeignScan;
fdwroutine->EndForeignScan = influxdbEndForeignScan;
/* support for EXPLAIN */
fdwroutine->ExplainForeignScan = influxdbExplainForeignScan;
fdwroutine->ExplainForeignModify = influxdbExplainForeignModify;
/* support for ANALYSE */
fdwroutine->AnalyzeForeignTable = influxdbAnalyzeForeignTable;
/* support for IMPORT FOREIGN SCHEMA */
fdwroutine->ImportForeignSchema = influxdbImportForeignSchema;
#if (PG_VERSION_NUM >= 100000)
/* Support functions for upper relation push-down */
fdwroutine->GetForeignUpperPaths = influxdbGetForeignUpperPaths;
#endif
PG_RETURN_POINTER(fdwroutine);
}
/*
* estimate_path_cost_size
* Get cost and size estimates for a foreign scan on given foreign relation
* either a base relation or a join between foreign relations.
*
* param_join_conds are the parameterization clauses with outer relations.
* pathkeys specify the expected sort order if any for given path being costed.
*
* The function returns the cost and size estimates in p_row, p_width,
* p_startup_cost and p_total_cost variables.
*/
static void
estimate_path_cost_size(PlannerInfo *root,
RelOptInfo *foreignrel,
List *param_join_conds,
List *pathkeys,
double *p_rows, int *p_width,
Cost *p_startup_cost, Cost *p_total_cost)
{
InfluxDBFdwRelationInfo *fpinfo =
(InfluxDBFdwRelationInfo *) foreignrel->fdw_private;
double rows;
double retrieved_rows;
int width;
Cost startup_cost;
Cost total_cost;
Cost cpu_per_tuple;
/*
* If the table or the server is configured to use remote estimates,
* connect to the foreign server and execute EXPLAIN to estimate the
* number of rows selected by the restriction+join clauses. Otherwise,
* estimate rows using whatever statistics we have locally, in a way
* similar to ordinary tables.
*/
if (fpinfo->use_remote_estimate)
{
ereport(ERROR, (errmsg("Remote estimation is unsupported")));
}
else
{
Cost run_cost = 0;
/*
* We don't support join conditions in this mode (hence, no
* parameterized paths can be made).
*/
Assert(param_join_conds == NIL);
/*
* Use rows/width estimates made by set_baserel_size_estimates() for
* base foreign relations and set_joinrel_size_estimates() for join
* between foreign relations.
*/
rows = foreignrel->rows;
width = foreignrel->reltarget->width;
/* Back into an estimate of the number of retrieved rows. */
retrieved_rows = clamp_row_est(rows / fpinfo->local_conds_sel);
/*
* We will come here again and again with different set of pathkeys
* that caller wants to cost. We don't need to calculate the cost of
* bare scan each time. Instead, use the costs if we have cached them
* already.
*/
if (fpinfo->rel_startup_cost > 0 && fpinfo->rel_total_cost > 0)
{
startup_cost = fpinfo->rel_startup_cost;
run_cost = fpinfo->rel_total_cost - fpinfo->rel_startup_cost;
}
else
{
Assert(foreignrel->reloptkind != RELOPT_JOINREL);
/* Clamp retrieved rows estimates to at most foreignrel->tuples. */
retrieved_rows = Min(retrieved_rows, foreignrel->tuples);
/*
* Cost as though this were a seqscan, which is pessimistic. We
* effectively imagine the local_conds are being evaluated
* remotely, too.
*/
startup_cost = 0;
run_cost = 0;
run_cost += seq_page_cost * foreignrel->pages;
startup_cost += foreignrel->baserestrictcost.startup;
cpu_per_tuple =
cpu_tuple_cost + foreignrel->baserestrictcost.per_tuple;
run_cost += cpu_per_tuple * foreignrel->tuples;
}
/*
* Without remote estimates, we have no real way to estimate the cost
* of generating sorted output. It could be free if the query plan
* the remote side would have chosen generates properly-sorted output
* anyway, but in most cases it will cost something. Estimate a value
* high enough that we won't pick the sorted path when the ordering
* isn't locally useful, but low enough that we'll err on the side of
* pushing down the ORDER BY clause when it's useful to do so.
*/
if (pathkeys != NIL)
{
startup_cost *= DEFAULT_FDW_SORT_MULTIPLIER;
run_cost *= DEFAULT_FDW_SORT_MULTIPLIER;
}
total_cost = startup_cost + run_cost;
}
/*
* Cache the costs for scans without any pathkeys or parameterization
* before adding the costs for transferring data from the foreign server.
* These costs are useful for costing the join between this relation and
* another foreign relation or to calculate the costs of paths with
* pathkeys for this relation, when the costs can not be obtained from the
* foreign server. This function will be called at least once for every
* foreign relation without pathkeys and parameterization.
*/
if (pathkeys == NIL && param_join_conds == NIL)
{
fpinfo->rel_startup_cost = startup_cost;
fpinfo->rel_total_cost = total_cost;
}
/*
* Add some additional cost factors to account for connection overhead
* (fdw_startup_cost), transferring data across the network
* (fdw_tuple_cost per retrieved row), and local manipulation of the data
* (cpu_tuple_cost per retrieved row).
*/
startup_cost += fpinfo->fdw_startup_cost;
total_cost += fpinfo->fdw_startup_cost;
total_cost += fpinfo->fdw_tuple_cost * retrieved_rows;
total_cost += cpu_tuple_cost * retrieved_rows;
/* Return results. */
*p_rows = rows;
*p_width = width;
*p_startup_cost = startup_cost;
*p_total_cost = total_cost;
}
/*
* influxdbGetForeignRelSize: Create a FdwPlan for a scan on the foreign table
*/
static void
influxdbGetForeignRelSize(PlannerInfo *root, RelOptInfo *baserel, Oid foreigntableid)
{
InfluxDBFdwRelationInfo *fpinfo;
ListCell *lc;
RangeTblEntry *rte = planner_rt_fetch(baserel->relid, root);
const char *namespace;
const char *relname;
const char *refname;
elog(DEBUG1, "influxdb_fdw : %s", __func__);
fpinfo = (InfluxDBFdwRelationInfo *) palloc0(sizeof(InfluxDBFdwRelationInfo));
baserel->fdw_private = (void *) fpinfo;
/* Base foreign tables need to be pushed down always. */
fpinfo->pushdown_safe = true;
/* Look up foreign-table catalog info. */
fpinfo->table = GetForeignTable(foreigntableid);
fpinfo->server = GetForeignServer(fpinfo->table->serverid);
/*
* Identify which baserestrictinfo clauses can be sent to the remote
* server and which can't.
*/
foreach(lc, baserel->baserestrictinfo)
{
RestrictInfo *ri = (RestrictInfo *) lfirst(lc);
if (influxdb_is_foreign_expr(root, baserel, ri->clause))
fpinfo->remote_conds = lappend(fpinfo->remote_conds, ri);
else
fpinfo->local_conds = lappend(fpinfo->local_conds, ri);
}
/*
* Identify which attributes will need to be retrieved from the remote
* server.
*/
#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);
/*
* Set cached relation costs to some negative value, so that we can detect
* when they are set to some sensible costs during one (usually the first)
* of the calls to estimate_path_cost_size().
*/
fpinfo->rel_startup_cost = -1;
fpinfo->rel_total_cost = -1;
/*
* If the table or the server is configured to use remote estimates,
* connect to the foreign server and execute EXPLAIN to estimate the
* number of rows selected by the restriction clauses, as well as the
* average row width. Otherwise, estimate using whatever statistics we
* have locally, in a way similar to ordinary tables.
*/
if (fpinfo->use_remote_estimate)
{
ereport(ERROR, (errmsg("Remote estimation is unsupported")));
}
else
{
/*
* 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 =
(10 * BLCKSZ) / (baserel->reltarget->width +
MAXALIGN(SizeofHeapTupleHeader));
}
/* 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, NIL,
&fpinfo->rows, &fpinfo->width,
&fpinfo->startup_cost, &fpinfo->total_cost);
}
/*
* Set the name of relation in fpinfo, while we are constructing it here.
* It will be used to build the string describing the join relation in
* EXPLAIN output. We can't know whether VERBOSE option is specified or
* not, so always schema-qualify the foreign table name.
*/
fpinfo->relation_name = makeStringInfo();
namespace = get_namespace_name(get_rel_namespace(foreigntableid));
relname = get_rel_name(foreigntableid);
refname = rte->eref->aliasname;
appendStringInfo(fpinfo->relation_name, "%s.%s",
quote_identifier(namespace),
quote_identifier(relname));
if (*refname && strcmp(refname, relname) != 0)
appendStringInfo(fpinfo->relation_name, " %s",
quote_identifier(rte->eref->aliasname));
}
/*
* influxdbGetForeignPaths
* Create possible scan paths for a scan on the foreign table
*/
static void
influxdbGetForeignPaths(PlannerInfo *root, RelOptInfo *baserel, Oid foreigntableid)
{
Cost startup_cost = 10;
Cost total_cost = baserel->rows + startup_cost;
elog(DEBUG1, "influxdb_fdw : %s", __func__);
/* Estimate costs */
total_cost = baserel->rows;
/* Create a ForeignPath node and add it as only possible path */
add_path(baserel, (Path *)
create_foreignscan_path(root, baserel,
#if PG_VERSION_NUM >= 90600
NULL, /* default pathtarget */
#endif
baserel->rows,
startup_cost,
total_cost,
NIL, /* no pathkeys */
NULL, /* no outer rel either */
NULL, /* no extra plan */
NULL)); /* no fdw_private data */
}
/*
* influxdbGetForeignPlan: Get a foreign scan plan node
*/
static ForeignScan *
influxdbGetForeignPlan(
PlannerInfo *root, RelOptInfo *baserel, Oid foreigntableid, ForeignPath *best_path, List *tlist, List *scan_clauses, Plan *outer_plan)
{
InfluxDBFdwRelationInfo *fpinfo = (InfluxDBFdwRelationInfo *) baserel->fdw_private;
Index scan_relid = baserel->relid;
List *fdw_private;
List *local_exprs = NULL;
List *remote_exprs = NULL;
List *params_list = NULL;
List *fdw_scan_tlist = NIL;
List *remote_conds = NIL;
StringInfoData sql;
List *retrieved_attrs;
ListCell *lc;
List *fdw_recheck_quals = NIL;
int for_update;
elog(DEBUG1, "influxdb_fdw : %s", __func__);
/*
* Build the query string to be sent for execution, and identify
* expressions to be sent as parameters.
*/
/* Build the query */
initStringInfo(&sql);
/*
* 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 influxdbGetForeignPaths. 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 only strip the RestrictInfo nodes from the
* local_exprs list, since appendWhereClause expects a list of
* RestrictInfos.
*/
if (baserel->reloptkind == RELOPT_BASEREL ||
baserel->reloptkind == RELOPT_OTHER_MEMBER_REL)
{
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 (influxdb_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);
/*
* For a base-relation scan, we have to support EPQ recheck, which
* should recheck all the remote quals.
*/
fdw_recheck_quals = remote_exprs;
}
}
else
{
/*
* Join relation or upper relation - set scan_relid to 0.
*/
scan_relid = 0;
/*
* For a join rel, baserestrictinfo is NIL and we are not considering
* parameterization right now, so there should be no scan_clauses for
* a joinrel or an upper rel either.
*/
Assert(!scan_clauses);
/*
* Instead we get the conditions to apply from the fdw_private
* structure.
*/
remote_exprs = extract_actual_clauses(fpinfo->remote_conds, false);
local_exprs = extract_actual_clauses(fpinfo->local_conds, false);
/*
* We leave fdw_recheck_quals empty in this case, since we never need
* to apply EPQ recheck clauses. In the case of a joinrel, EPQ
* recheck is handled elsewhere --- see influxdbGetForeignJoinPaths().
* If we're planning an upperrel (ie, remote grouping or aggregation)
* then there's no EPQ to do because SELECT FOR UPDATE wouldn't be
* allowed, and indeed we *can't* put the remote clauses into
* fdw_recheck_quals because the unaggregated Vars won't be available
* locally.
*/
/* Build the list of columns to be fetched from the foreign server. */
fdw_scan_tlist = influxdb_build_tlist_to_deparse(baserel);
/*
* Ensure that the outer plan produces a tuple whose descriptor
* matches our scan tuple slot. This is safe because all scans and
* joins support projection, so we never need to insert a Result node.
* Also, remove the local conditions from outer plan's quals, lest
* they will be evaluated twice, once by the local plan and once by
* the scan.
*/
if (outer_plan)
{
ListCell *lc;
/*
* Right now, we only consider grouping and aggregation beyond
* joins. Queries involving aggregates or grouping do not require
* EPQ mechanism, hence should not have an outer plan here.
*/
Assert(baserel->reloptkind != RELOPT_UPPER_REL);
outer_plan->targetlist = fdw_scan_tlist;
foreach(lc, local_exprs)
{
Join *join_plan = (Join *) outer_plan;
Node *qual = lfirst(lc);
outer_plan->qual = list_delete(outer_plan->qual, qual);
/*
* For an inner join the local conditions of foreign scan plan
* can be part of the joinquals as well.
*/
if (join_plan->jointype == JOIN_INNER)
join_plan->joinqual = list_delete(join_plan->joinqual,
qual);
}
}
}
/*
* Build the query string to be sent for execution, and identify
* expressions to be sent as parameters.
*/
initStringInfo(&sql);
influxdbDeparseSelectStmtForRel(&sql, root, baserel, fdw_scan_tlist,
remote_exprs, best_path->path.pathkeys,
false, &retrieved_attrs, ¶ms_list);
for_update = false;
if (baserel->relid == root->parse->resultRelation &&
(root->parse->commandType == CMD_UPDATE ||
root->parse->commandType == CMD_DELETE))
{
/* Relation is UPDATE/DELETE target, so use FOR UPDATE */
for_update = true;
}
/*
* Build the fdw_private list that will be available to the executor.
* Items in the list must match enum FdwScanPrivateIndex, above.
*/
fdw_private = list_make4(makeString(sql.data), retrieved_attrs, makeInteger(for_update),
fdw_scan_tlist);
/*
* 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,
fdw_scan_tlist, fdw_recheck_quals, outer_plan
);
}
/*
* influxdbBeginForeignScan: Initiate access to the database
*/
static void
influxdbBeginForeignScan(ForeignScanState *node, int eflags)
{
InfluxDBFdwExecState *festate = NULL;
EState *estate = node->ss.ps.state;
ForeignScan *fsplan = (ForeignScan *) node->ss.ps.plan;
int numParams;
elog(DEBUG1, "influxdb_fdw : %s", __func__);
/*
* We'll save private state in node->fdw_state.
*/
festate = (InfluxDBFdwExecState *) palloc(sizeof(InfluxDBFdwExecState));
node->fdw_state = (void *) festate;
festate->rowidx = 0;
/* Stash away the state info we have already */
festate->query = strVal(list_nth(fsplan->fdw_private, 0));
festate->retrieved_attrs = list_nth(fsplan->fdw_private, 1);
festate->for_update = intVal(list_nth(fsplan->fdw_private, 2)) ? true : false;
festate->tlist = (List *) list_nth(fsplan->fdw_private, 3);
festate->cursor_exists = false;
festate->temp_cxt = AllocSetContextCreate(estate->es_query_cxt,
"influxdb_fdw temporary data",
ALLOCSET_SMALL_SIZES);
/* Prepare for output conversion of parameters used in remote query. */
numParams = list_length(fsplan->fdw_exprs);
festate->numParams = numParams;
if (numParams > 0)
prepare_query_params((PlanState *) node,
fsplan->fdw_exprs,
numParams,
&festate->param_flinfo,
&festate->param_exprs,
&festate->param_values,
&festate->param_types,
&festate->param_influxdb_types,
&festate->param_influxdb_values);
}
static char *
get_column_name(Oid relid, int attnum)
{
List *options = NULL;
ListCell *lc_opt;
char *colname = NULL;
options = GetForeignColumnOptions(relid, attnum);
foreach(lc_opt, options)
{
DefElem *def = (DefElem *) lfirst(lc_opt);
if (strcmp(def->defname, "column_name") == 0)
{
colname = defGetString(def);
break;
}
}
if (colname == NULL)
colname = get_attname(relid, attnum
#if (PG_VERSION_NUM >= 110000)
,
false
#endif
);
return colname;
}
static void
make_tuple_from_result_row(InfluxDBRow * result_row,
InfluxDBResult * result,
TupleDesc tupleDescriptor,
Datum *row,
bool *is_null,
Oid relid,
InfluxDBFdwExecState * festate,
bool is_agg)
{
ListCell *lc = NULL;
int attid = 0;
List *retrieved_attrs = festate->retrieved_attrs;
ListCell *targetc;
memset(row, 0, sizeof(Datum) * tupleDescriptor->natts);
memset(is_null, true, sizeof(bool) * tupleDescriptor->natts);
targetc = list_head(festate->tlist);
foreach(lc, retrieved_attrs)
{
int attnum = lfirst_int(lc) - 1;
Oid pgtype = TupleDescAttr(tupleDescriptor, attnum)->atttypid;
int32 pgtypmod = TupleDescAttr(tupleDescriptor, attnum)->atttypmod;
int result_idx = 0;
char *colname = NULL;
if (is_agg)
{
/* Aggregate push down case */
/*
* This column is not explicitly added to InfluxDB query, but
* InfluxDB returns implicitly
*/
Expr *target = ((TargetEntry *) lfirst(targetc))->expr;
if (IsA(target, Var))
{
/* GROUP BY target variable */
int i;
char *name = get_column_name(relid, ((Var *) target)->varattno);
int nfield = result->ncol - result->ntag;
/*
* Values of GROUP BY tag are stored in the order of
* result->tagkeys at the last of result row. We will find
* that index
*/
for (i = 0; i < result->ntag; i++)
{
if (strcmp(name, result->tagkeys[i]) == 0)
{
result_idx = nfield + i;
break;
}
}
}
else if (IsA(target, FuncExpr) &&
strcmp(influxdb_get_function_name(((FuncExpr *) target)->funcid), "influx_time") == 0)
{
/* Time column corresponding to influx_time */
result_idx = 0;
}
else if (IsA(target, Aggref))
{
attid++;
result_idx = attid;
}
else
{
/*
* Other GROUP BY target is not supported
*/
elog(ERROR, "not supported");
}
targetc = lnext(targetc);
}
else
{
colname = get_column_name(relid, attnum + 1);
if (INFLUXDB_IS_TIME_COLUMN(colname))
{
result_idx = 0;
}
else
{
attid++;
result_idx = attid;
}
}
if (result_row->tuple[result_idx] != NULL)
{
is_null[attnum] = false;
row[attnum] = influxdb_convert_to_pg(pgtype, pgtypmod,
result_row->tuple, result_idx);
}
}
}
/*
* influxdbIterateForeignScan: Iterate and get the rows one by one from
* InfluxDB and placed in tuple slot
*/
static TupleTableSlot *
influxdbIterateForeignScan(ForeignScanState *node)
{
InfluxDBFdwExecState *festate = (InfluxDBFdwExecState *) node->fdw_state;
TupleTableSlot *tupleSlot = node->ss.ss_ScanTupleSlot;
EState *estate = node->ss.ps.state;
TupleDesc tupleDescriptor = tupleSlot->tts_tupleDescriptor;
influxdb_opt *options;
struct InfluxDBQuery_return volatile ret;
struct InfluxDBResult volatile *result;
ForeignScan *fsplan = (ForeignScan *) node->ss.ps.plan;
RangeTblEntry *rte;
int rtindex;
bool is_agg;
elog(DEBUG1, "influxdb_fdw : %s", __func__);
/*
* Identify which user to do the remote access as. This should match what
* ExecCheckRTEPerms() does. In case of a join or aggregate, use the
* lowest-numbered member RTE as a representative; we would get the same
* result from any.
*/
if (fsplan->scan.scanrelid > 0)
{
rtindex = fsplan->scan.scanrelid;
is_agg = false;
}
else
{
rtindex = bms_next_member(fsplan->fs_relids, -1);
is_agg = true;
}
rte = rt_fetch(rtindex, estate->es_range_table);
/* table = GetForeignTable(rte->relid); */
/* Fetch the options */
options = influxdb_get_options(rte->relid);
/*
* If this is the first call after Begin or ReScan, we need to create the
* cursor on the remote side. Binding parameters is done in this function.
*/
if (!festate->cursor_exists)
create_cursor(node);
ExecClearTuple(tupleSlot);
if (festate->rowidx == 0)
{
int i;
PG_TRY();
{
MemoryContext oldcontext;
ret = InfluxDBQuery(festate->query, options->svr_address, options->svr_port,
options->svr_username, options->svr_password,
options->svr_database,
festate->param_influxdb_types,
festate->param_influxdb_values,
festate->numParams);
if (ret.r1 != NULL)
{
char *err = pstrdup(ret.r1);
free(ret.r1);
ret.r1 = err;
elog(ERROR, "influxdb_fdw : %s", err);
}
result = &ret.r0;
elog(DEBUG1, "influxdb_fdw : query: %s %d", festate->query, festate->numParams);
/* festate->rows need longer context than per tuple */
oldcontext = MemoryContextSwitchTo(estate->es_query_cxt);
festate->row_nums = result->nrow;
festate->rows = palloc(sizeof(Datum *) * result->nrow);
festate->rows_isnull = palloc(sizeof(bool *) * result->nrow);
for (i = 0; i < result->nrow; i++)
{
festate->rows[i] = palloc(sizeof(Datum) * tupleDescriptor->natts);
festate->rows_isnull[i] = palloc(sizeof(bool) * tupleDescriptor->natts);
make_tuple_from_result_row(&(result->rows[i]),
(struct InfluxDBResult *) result,
tupleDescriptor,
festate->rows[i],
festate->rows_isnull[i],
rte->relid,
festate,
is_agg);
}
MemoryContextSwitchTo(oldcontext);
InfluxDBFreeResult((InfluxDBResult *) result);
}
PG_CATCH();
{
if (ret.r1 == NULL)