>From 92596ee8cda043cbc37cd27d4ec668f624a49d6e Mon Sep 17 00:00:00 2001 From: Kyotaro Horiguchi Date: Tue, 30 Jun 2015 15:29:46 +0900 Subject: [PATCH] Add foreign table option to set fetch size. --- contrib/postgres_fdw/option.c | 2 ++ contrib/postgres_fdw/postgres_fdw.c | 31 +++++++++++++++++++++++++++---- 2 files changed, 29 insertions(+), 4 deletions(-) diff --git a/contrib/postgres_fdw/option.c b/contrib/postgres_fdw/option.c index 7547ec2..793239d 100644 --- a/contrib/postgres_fdw/option.c +++ b/contrib/postgres_fdw/option.c @@ -153,6 +153,8 @@ InitPgFdwOptions(void) /* updatable is available on both server and table */ {"updatable", ForeignServerRelationId, false}, {"updatable", ForeignTableRelationId, false}, + /* fetch_size is available on table (XXX: also server may have it.) */ + {"fetch_size", ForeignTableRelationId, false}, {NULL, InvalidOid, false} }; diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c index 40cac3b..e01213e 100644 --- a/contrib/postgres_fdw/postgres_fdw.c +++ b/contrib/postgres_fdw/postgres_fdw.c @@ -152,6 +152,7 @@ typedef struct PgFdwScanState 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 */ + int fetch_size; /* number of tuples to request by one fetch */ /* for storing result tuples */ HeapTuple *tuples; /* array of currently-retrieved tuples */ @@ -945,6 +946,31 @@ postgresBeginForeignScan(ForeignScanState *node, int eflags) server = GetForeignServer(table->serverid); user = GetUserMapping(userid, server->serverid); + fsstate->fetch_size = -1; + foreach(lc, table->options) + { + DefElem *def = (DefElem *) lfirst(lc); + + /* Does anyone specify negatives? Who cares? */ + if (strcmp(def->defname, "fetch_size") == 0) + { + char *ep = NULL; + char *defstr = defGetString(def); + + fsstate->fetch_size = strtol(defstr, &ep, 10); + if (*ep || ep == defstr) + { + elog(WARNING, + "Option \"%s\" must be a positive integer (foreign table \"%s\") : \"%s\"", + def->defname, get_rel_name(table->relid), defstr); + fsstate->fetch_size = -1; /* Use default */ + } + break; + } + } + if (fsstate->fetch_size < 1) + fsstate->fetch_size = 100; /* default size */ + /* * Get connection to the foreign server. Connection manager will * establish new connection if necessary. @@ -2092,15 +2118,12 @@ fetch_more_data(PgFdwScanState *fsstate, fetch_mode cmd) { PgFdwConn *conn = fsstate->conn; char sql[64]; - int fetch_size; + int fetch_size = fsstate->fetch_size; int numrows, addrows, restrows; HeapTuple *tmptuples; int i; int fetch_buf_size; - /* The fetch size is arbitrary, but shouldn't be enormous. */ - fetch_size = 100; - /* Make the query to fetch tuples */ snprintf(sql, sizeof(sql), "FETCH %d FROM c%u", fetch_size, fsstate->cursor_number); -- 1.8.3.1