XLog vs SSD [Was: Re: random write in xlog?]

>>>>> "JJ" == Jeff Janes <jeff(dot)janes(at)gmail(dot)com> writes:

JJ> Anyway, the writes are logically sequentially, but not physically.
JJ> If I remember correctly, it always writes out full blocks, even if
JJ> the last part of the block has not yet been filled with new data.
JJ> When the remainder gets filled, it then writes out the full block
JJ> again, both the already written and the new part.

What does that mean for use of a flash SSD for the xlog dir?

Does the block writing mesh up well with the usage pattern a flash
SSD needs to maximize lifespan?

I'd love a dram ssd for pg_xlog and the journals for the other
filesystems, but they cost too much.

-JimC
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James Cloos <cloos(at)jhcloos(dot)com> OpenPGP: 1024D/ED7DAEA6