Parallel BG search does not always work
|||Spider for MySQL||
Spider engine version 3.0.
The parallel BG search does not always work, depending on the query one asks.
On a table with one primary key column (id) and one data column (data), the following
queries are correctly run in parallel if BG search is on:
id ranges from 3000000000 to 8500000000
data ranges from 0 to 1000
SELECT * from foo where id < 3000000010
SELECT * from foo where data > 1000.1
however the following query is run in sequential order, where each node is asked for
SELECT * from foo where data > 999.9
SELECT * from foo where id > 3000000010
SELECT * from foo where id < 5000000010
With the data column the behavior seems to be dependent on the maximum value in the
table. I have no idea though, why the second and third query on the primary key column do
not run in parallel. Somehow this seems correlated with the amount of data returned (does
the optimiser play a role in this?)
Let me know if you need more information.
|Changed in spiderformysql:|
|assignee:||nobody → Kentoku SHIBA (kentokushiba)|
|importance:||Undecided → Medium|
|status:||New → In Progress|