Re: [HACKERS] Extending constraint exclusion for implied constraints/conditions

2014-07-08 Thread Ashutosh Bapat
On Mon, Jul 7, 2014 at 11:46 PM, Greg Stark st...@mit.edu wrote: On Mon, Jul 7, 2014 at 3:07 PM, Tom Lane t...@sss.pgh.pa.us wrote: I doubt it. The extra code isn't the problem so much, it's the extra planning cycles spent trying to make proofs that will usually fail. What you propose

Re: [HACKERS] Extending constraint exclusion for implied constraints/conditions

2014-07-08 Thread Tom Lane
Ashutosh Bapat ashutosh.ba...@enterprisedb.com writes: On Mon, Jul 7, 2014 at 7:37 PM, Tom Lane t...@sss.pgh.pa.us wrote: I doubt it. The extra code isn't the problem so much, it's the extra planning cycles spent trying to make proofs that will usually fail. What you propose will create a

Re: [HACKERS] Extending constraint exclusion for implied constraints/conditions

2014-07-08 Thread Ashutosh Bapat
On Tue, Jul 8, 2014 at 7:57 PM, Tom Lane t...@sss.pgh.pa.us wrote: Ashutosh Bapat ashutosh.ba...@enterprisedb.com writes: On Mon, Jul 7, 2014 at 7:37 PM, Tom Lane t...@sss.pgh.pa.us wrote: I doubt it. The extra code isn't the problem so much, it's the extra planning cycles spent trying to

[HACKERS] Extending constraint exclusion for implied constraints/conditions

2014-07-07 Thread Ashutosh Bapat
Hi, Here's a table I have postgres=# \d+ tab1 Table public.tab1 Column | Type | Modifiers | Storage | Stats target | Description +-+---+-+--+- val| integer | | plain | | val2 |

Re: [HACKERS] Extending constraint exclusion for implied constraints/conditions

2014-07-07 Thread Tom Lane
Ashutosh Bapat ashutosh.ba...@enterprisedb.com writes: Right now, constraint exclusion code looks only at the provided conditions. If we want avoid table scan based on constraints in the above example, it will need to look at the implied conditions as well. E.g. val2 30 AND val = val2 = val

Re: [HACKERS] Extending constraint exclusion for implied constraints/conditions

2014-07-07 Thread Greg Stark
On Mon, Jul 7, 2014 at 3:07 PM, Tom Lane t...@sss.pgh.pa.us wrote: I doubt it. The extra code isn't the problem so much, it's the extra planning cycles spent trying to make proofs that will usually fail. What you propose will create a combinatorial explosion in the number of proof paths to be

Re: [HACKERS] Extending constraint exclusion for implied constraints/conditions

2014-07-07 Thread Ashutosh Bapat
On Mon, Jul 7, 2014 at 7:37 PM, Tom Lane t...@sss.pgh.pa.us wrote: Ashutosh Bapat ashutosh.ba...@enterprisedb.com writes: Right now, constraint exclusion code looks only at the provided conditions. If we want avoid table scan based on constraints in the above example, it will need to look