For membership/equality predicates (also partial, for multiple columns) you could take a look at bloom indexes: they are quite efficient in terms of space footprint, you can even choose how long is the signature for each entry and how is distributed among the columns.
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On Wed, 8 Feb 2023 at 23:15, Siddharth Jain <siddhsql@xxxxxxxxx> wrote:
OK so in that case we are left with the B-Tree index.If the B-Tree index will be so large that it cannot fit in memory, then is it worth creating it at all? Are there any established patterns here?On Wed, Feb 8, 2023 at 1:21 PM Christophe Pettus <xof@xxxxxxxxxxxx> wrote:
> On Feb 8, 2023, at 13:17, Siddharth Jain <siddhsql@xxxxxxxxx> wrote:
>
> As I explained in my question that is indeed our dilemma. Our insertion order will not be equal to index order. i.e., referring to your response:
>
> > who's data is added in the same order as the key in the BRIN index
>
> does NOT hold.
A BRIN index is not a good choice in this case. You can CLUSTER the data on an index, but that's a one-time operation: PostgreSQL will not maintain that order after the CLUSTER. If the number of rows in the table at the time of the CLUSTER is much larger than the number that are inserted between CLUSTER operations, then a BRIN index might be useful, but clustering a very large table is an expensive operation, and requires an exclusive lock on the table while it is being done.
