From: | Pierre-Frédéric Caillaud <lists(at)boutiquenumerique(dot)com> |
---|---|
To: | performance(at)postgresql(dot)org |
Subject: | Question on Byte Sizes |
Date: | 2004-09-10 06:36:16 |
Message-ID: | opsd3lyqygcq72hf@musicbox |
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Thread: | |
Lists: | pgsql-performance |
Hello,
* I need information on the size of pg ARRAY[]'s :
I did not find any info in the Docs on this.
How many bytes does an array take on disk ?
Is there a difference between an array of fixed size elements like
integers, and an array of variable length elements like text ? is there a
pointer table ? Or are the elements packed together ?
Is there any advantage in using a smallint[] over an integer[] regarding
size ?
Does a smallint[] with 2 elements really take 12 bytes ?
* On Alignment :
The docs say fields are aligned on 4-bytes boundaries.
Does this mean that several consecutive smallint fields will take 4 bytes
each ?
What about seleral consecutive "char" fields ? 4 bytes each too ?
I ask this because I'll have a lot of columns with small values to store
in a table, and
would like it to be small and to fit in the cache.
Thanks for any info.
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