Hullo all,
Run on a single processor, the following query is quite fast:
// Select Statement
sprintf(sql_statements,
"select lp.%s, lp.%s, lp.%s, lp.%s, pb.%s from %s lp, %s pb "
"where lp.%s > ? and lp.%s=pb.%s "
"order by lp.%s, lp.%s, pb.%s",
ARTID_LATENT_PARENT_XPOS,
ARTID_LATENT_PARENT_YPOS,
ARTID_LATENT_PARENT_RADIUS_OF_INFLUENCE,
ARTID_LATENT_PARENT_FR_TIME_STAMP,
ARTID_LATENT_PARENT_PIXEL_BIN_NUM,
ARTID_LATENT_PARENT_TABLE,
ARTID_LATENT_PARENT_PIXEL_BIN_TABLE,
ARTID_LATENT_PARENT_FR_TIME_STAMP,
ARTID_LATENT_PARENT_SOURCE_ID,
ARTID_LATENT_PARENT_SOURCE_ID,
ARTID_LATENT_PARENT_XPOS,
ARTID_LATENT_PARENT_YPOS,
ARTID_LATENT_PARENT_PIXEL_BIN_NUM);
When concurrency is introduced (simply running the query on several
processors against the same database - say 300 instances of it) causes
a massive slow down with significant fluctuations in time between
instances. Only reads are done (i.e. queries) - no writes. How does
one optimize concurrency in sqlite3
The database is opened as follows:
//sql_rc = sqlite3_open(database_name, &sql_db);
sql_rc = sqlite3_open_v2(database_name,
&sql_db,
SQLITE_OPEN_READONLY,
NULL);
if (sql_rc != SQLITE_OK) {
fprintf(stderr, "Function:%s can't open database:%s, error:%s\n",
FLAG_ON_LATENT, database_name,
sqlite3_errmsg(sql_db));
sqlite3_close(sql_db);
return(FAIL);
}
-rosemary.
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