[sqlite] Will SQLite break a join query?
Sairam Gaddam wrote: > I know that SQLite will perform some internal select statements when > executing a join query but will it break a join query and execute in parts > ??? SQLite executes all joins in parts, i.e., it is not possible to do more than one lookup of a joined field. (SQLite implements only nested loop joins.) However, SQLite tries to compute output rows dynamically, i.e., it takes the first row of the first table, looks up the matching row(s) in the second table and then in other joined tables, outputs the result row, and then continues with the second row. In other words, the temporary result of a join between all the rows in two tables is not actually stored as a whole anywhere (unless needed for sorting or grouping). Regards, Clemens
[sqlite] Will SQLite break a join query?
I know that SQLite will perform some internal select statements when executing a join query but will it break a join query and execute in parts ??? For example if I join 10 tables, will it perform join of 8 and 2 tables at once and in turn join the result of those two joins?
[sqlite] Will SQLite break a join query?
You can get SQLite to show exactly what it's doing using "explain", see http://sqlite.org/opcode.html On Thu, Jun 25, 2015 at 10:16 PM, Sairam Gaddam wrote: > I know that SQLite will perform some internal select statements when > executing a join query but will it break a join query and execute in parts > ??? > > For example if I join 10 tables, will it perform join of 8 and 2 tables at > once and in turn join the result of those two joins? > ___ > sqlite-users mailing list > sqlite-users at mailinglists.sqlite.org > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users >
