ERROR 8617: Request size too big (MaxParsedQuerySizeMB)

vasmez81vasmez81 Registered User
edited April 23 in Vertica Forum

Hello!
I have a problem with selecting data from table which contains varchar (64000) records.

select start_timestamp, request, ... from projection_used where start_timestamp > '...'
ERROR 8617:  Request size too big
DETAIL:  Total allocated memory (MiB) = 1024.006 is about to exceed limit imposed by MaxParsedQuerySizeMB (MiB) = 1024.000

Column "request" has the type varchar (64000)

Every hour we save new records from query_requests and dc_projection_used to a regular table. And then we make extracts from the table for technical analysis.
Everything worked fine for over a year (9.0, 9.1), but after upgrading to 9.2 there was a problem.
If the incremental extract contains more than 200k-400k records, then this leads to problems with the MaxParsedQuerySizeMB value = 1 GB

I tried to increase the value, but with a large interval of data (29M records) this stops helping even with 16GB

Vertica version is v9.2.0-0 CE

Comments

  • Jim_KnicelyJim_Knicely Administrator, Moderator, Employee, Registered User, VerticaExpert admin

    Every time you change the value of MaxParsedQuerySizeMB, only new sessions created afterwards will be affected.

  • vasmez81vasmez81 Registered User
    Every time you change the value of MaxParsedQuerySizeMB, only new sessions created afterwards will be affected.
    

    That's not the problem.
    1. It's very likely that a vertica 9.2 has a problem with selecting rows which contains long values. In my case it's varchar(64000) and ~300k rows with MaxParsedQuerySizeMB = 1024
    2. Why do I need to increase the size of MaxParsedQuerySizeMB for simple selects?
    Table "projection_used" - is a regular non-system table, which contains history of v_internal.dc_projections_used

  • Jim_KnicelyJim_Knicely Administrator, Moderator, Employee, Registered User, VerticaExpert admin
    edited May 28

    Vertica 9.2 started checking the MaxParsedQuerySizeMB parameter which is why you did not get the error in 9.0 and 9.1.

    You can disable this check by setting MaxParsedQuerySizeMB to 0.

    dbadmin=> SELECT set_config_parameter('MaxParsedQuerySizeMB', 0);
        set_config_parameter
    ----------------------------
     Parameter set successfully
    (1 row)
    

    There is an open Jira ticket to get this issue addressed. I will keep this post updated when a fix is released!

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