Question on Byte Sizes
От | Pierre-Frédéric Caillaud |
---|---|
Тема | Question on Byte Sizes |
Дата | |
Msg-id | opsd3lyqygcq72hf@musicbox обсуждение исходный текст |
Ответ на | Re: Multiple Uniques (Tom Lane <tgl@sss.pgh.pa.us>) |
Список | 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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