VOPS-2.0 - Mailing list pgsql-announce

Hi,

I want to introduce new version of VOPS extension for Postgres 
(vectorized operations) providing new, more convenient way of usage:
auto-substitution of projections.

The idea of VOPS was to use special vector (tile) types instead of 
standard scalar types, i.e. vops_float8 instead of float8.
Such vector types implement all standard arithmetic operators and make 
it possible to use them in queries almost in the same way as scalar types.
But each such operator or aggregate function proceed hundred of values, 
minimizing interpretation overhead of Postgres executor.
This is why VOPS provides more than ten times performance improvement 
for analytic queries performing filtering and aggregation (like Q1/Q6 
TPC-H queries).
It was possible to create VOPS tables explicitly but now VOPS provides 
much more convenient way: VOPS projections.

It is assumed that data is stored in normal Postgres table and user can 
define one or more projections of this table (as in Vertica).
Each projection consists of some subset of attributes of original table 
and some of this attributes preserve the attribute type of original table
(them are referred as "scalar attributes"), while other use instead 
correspondent VOPS types ("vector attributes").
Scalar attributes of projection can be used for sorting, grouping or 
joining. Vector attributes can be used in where clause and in target 
list (including aggregate functions).

The main main advantage of new version of VOPS is that it allows to 
automatically substitute queries to original table with queries to one 
of its projections.
So client should not know about presence of VOPS projection and somehow 
change used queries.
VOPS projections are created using create_projection() function which 
specifies list of vector and scalar attributes:

select 

create_projection('vops_lineitem','lineitem',array['l_shipdate','l_quantity','l_extendedprice','l_discount','l_tax'],array['l_returnflag','l_linestatus']);

In future may be "CREATE PROJECTION..." clause will be supported, but it 
requires changes in PostgreSQL core and can't be implemented at 
extension level.

If "vops.auto_substitute_projections" option is set to true, then parse 
hook installed by VOPS tries all projections defined for the table
and if original table can be substituted by one of this projections, 
then alternative query is executed.

By default "vops.auto_substitute_projections" is switched off, because 
VOPS doesn't enforce consistency of projections with original table.
As with materialized view, refresh of projections should by done 
manually by user. Certainly it is possible to do it using triggers, but 
it will be very inefficient:
only bulk updates can provide good update and select performance.
create_projection(XXX) generates XXX_refresh() function which can be 
used to periodically update the projection.

VOPS supports all version of Postgres starting from 10.0 and can be 
downloaded from github repository:
https://github.com/postgrespro/vops.git

-- 
Konstantin Knizhnik
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company