Re: Storage Model for Partitioning - Mailing list pgsql-hackers

From Richard Huxton
Subject Re: Storage Model for Partitioning
Date
Msg-id 47875439.2050309@archonet.com
Whole thread Raw
In response to Storage Model for Partitioning  (Simon Riggs <simon@2ndquadrant.com>)
Responses Re: Storage Model for Partitioning  (Csaba Nagy <nagy@ecircle-ag.com>)
Re: Storage Model for Partitioning  (Simon Riggs <simon@2ndquadrant.com>)
List pgsql-hackers
More dumb user questions...

Simon Riggs wrote:
> 1. Partitions are Contiguous Ranges of Blocks
> 
> Partitions are a simple subset of a table, i.e. a contiguous range of
> blocks within the main block range of the table.

> b) Fixed partitioning - we define partitions as static ranges of blocks,
> which may leave us with holes in the range of BlockNumbers, plus each
> partition has a maximum size that it cannot expand beyond. Probably
> unacceptable.

Clearly not going to make anyone happy if you can't fit 1.1GB of data 
into your partition.

Is the following basically the same as option #3 (multiple RelFileNodes)?

1. Make an on-disk "chunk" much smaller (e.g. 64MB). Each chunk is a 
contigous range of blocks.
2. Make a table-partition (implied or explicit constraints) map to 
multiple "chunks".
That would reduce fragmentation (you'd have on average 32MB's worth of 
blocks wasted per partition) and allow for stretchy partitions at the 
cost of an extra layer of indirection.

For the single-partition case you'd not need to split the file of 
course, so it would end up looking much like the current arrangement.

--   Richard Huxton  Archonet Ltd


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