On Thu, 2002-12-19 at 13:10, george young wrote:
> [linux, 700MHz athlon, 512MB RAM, 700GB 10kRPM SCSI HW RAID, postgresql 7.2]
> We're setting up a DB of IC test data, which is very simple and regular, but large.
> One project (we get three or four per year) has ~4 giga bits, each specified by
> a few small integer values, e.g.:
> Name Type Values
> ----------------------
> wafer int 1-50
> die_row int 2-7
> die_col int 2-7
> testtype string (~10 different short strings)
> vdd int 0-25
> bit_col int 0-127
> bit_row int 0-511
> value bit 0 or 1
>
> with 4 billion(4e9) rows. I would guess to make wafer, die_row, etc. be of
> type "char", probably testtype a char too with a separate testtype lookup table.
> Even so, this will be a huge table.
How many records per day will be inserted?
Will they ever be updated?
Do you have to have *ALL* 4 billion records in the same table at the
same time? As Josh Berkus mentioned, wafer thru bit_col can be
converted to INT2, if you make testtype use a lookup table; thus, each
tuple could be shrunk to 20 bytes, plus 24 bytes per tuple (in v7.3)
that would make the table a minimum of 189 billion bytes, not
including index!!!
Rethink your solution...
One possibility would to have a set of tables, with names like:
TEST_DATA_200301
TEST_DATA_200302
TEST_DATA_200303
TEST_DATA_200304
TEST_DATA_200305
TEST_DATA_200306
TEST_DATA_200307
TEST_DATA_<etc>
Then, each month do "CREATE VIEW TEST_DATA AS TEST_DATA_yyyymm" for the
current month.
> Questions: How much overhead will there be in the table in addition to the
> 9 bytes of data I see? How big will the primary index on the first seven columns
> be? Will this schema work at all?
>
> Of course, we could pack 128 bits into an 8 byte "text" field (or should we use bit(128)?),
> but lose some ease of use, especially for naive (but important) users.
>
> Comments, suggestions?
>
> -- George
>
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