Re: SELECT queries stalling insert/update on table

[Thomas Mueller]

Hi,

The best solution would be to speed up the queries of course. If you can't do that:

By default, H2 does not execute multiple statements concurrently. You would have to enable multi-threading by appending ";MULTI_THREADED=TRUE" to the database URL (see the docs).

Regards,

Thomas

On Tuesday, July 10, 2012, abhi wrote:

We are using H2 in-memory database for a application, which has 500+ insert/updates per second operation on a single table. The application is expected to eventually handle 2000+ insert/update per second. 

It is observed that SELECT queries, which takes long time (say 2+ seconds) to execute, stall insert/update operations until they have not completed execution.

We do not want  SELECT queries to block insert/update operations on the table. To achieve concurrency, I tried different configurations such as LOCK_MODE=3 or MVCC=TRUE. However, they do not fix the issue.

I would like to know if there is a way to run concurrent select and insert/update operation on the table?

We are using 1.3.xxx version of the H2 database.

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[abhi]

I was able to speed the execution of queries by adding indexes.
Also, I added MULTI_THREADED=TRUE to the database URL. However, I am still observing that whenever SELECT queries take sometime for execution, the insert/update operation on the table stalls. Was wondering whether the  implementation of H2 database is single-threaded behind the scene.

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