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From alex kamil <>
Subject Re: Phoenix and SQL In clauses
Date Thu, 29 May 2014 23:36:38 GMT
* maximum *number *of elements

On Thu, May 29, 2014 at 7:34 PM, alex kamil <> wrote:

> forgot to mention, to determine maximum value of elements in an IN clause it's
> important to know how many elements each of the M queries actually returns
> and the size of the resultsets for each; while the number of elements in IN
> clause can be  up to X , the number of  rows retrieved will be up to Y,
>  and the MAX for X will depend on Y
> On Wed, May 28, 2014 at 1:53 PM, alex kamil <> wrote:
>> Dmitry,
>> we've tried something similar, on a table with a few hundreds of VARCHAR
>> columns getting   >30k items in IN clause was starting to exceed 60 sec, if
>> I remember correctly,
>> it basically becomes an IO bottleneck getting the huge resultsets back to
>> the client
>> this was a workaround we used before JOINs became available in phoenix -
>> pulled a subset of data to the client  using a batch of M queries with N
>> elements each, and did a join on client side in HSQLDB, which was messy and
>> inefficient
>> with phoenix 3.0 we switched to using joins on server side and avoid this
>> scenario completely
>> Alex
>> On Wed, May 28, 2014 at 1:27 PM, Dmitry Goldenberg <
>>> wrote:
>>> Hi,
>>> I was wondering that the maximum value of elements in an IN clause is,
>>> in Phoenix.  Also, from the performance standpoint, if I were to batch up
>>> the items into M statements of N elements per In clause and execute
>>> multiple statements to avoid ever hitting the max, what may be an optimal
>>> value for N, considering that I only have a few relatively small column
>>> values (int, varchar, timestamp) per statement?
>>> Thanks.
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