Re: A thought on Index Organized Tables

Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Takahiro Itagaki <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp> writes:
> > Instead, how about excluding columns in primary keys from table data?
>
> How will you implement "select * from mytable" ? Or even
> "select * from mytable where non_primary_key = something" ?

Use index full scans. We can do it even for now with enable_seqscan = off.
Of course, it requires an additional step to merge index keys and heap tuples.

Also, we're using the same technique for TOASTed values. The cost can be
compared with "select * from mytable where toasted_value = something", no?

> If you can't do either of those without great expense, I think
> a savings on primary-key lookups is not going to be adequate
> recompense.

I don't think it will be the default, but it would be a reasonable trade-off
for users who want IOTs, unless they often scan the whole table.

Regards,
---
Takahiro Itagaki
NTT Open Source Software Center