Add user search methods by email/name fragment

[akorneta]

What does this PR do?

Adds user search methods by email/name part.
Adds pattern index on email for postgresql.

What issues does this PR fix or reference?

is needed for: issue

Changelog

add user search methods by email/name fragment

Release Notes

n/a

Docs PR

n/a

[skabashnyuk]

@akorneta can you provide pgsql explain for each query?
Can you explain how these methods will be used? how often?

[akorneta]

@skabashnyuk this methods are needed for onprem admins and in one use case for saas admin so I think it is not the most frequent query.

explanations:

by email part

Seq Scan on usr u  (cost=0.00..10.53 rows=1 width=2088) (actual time=0.011..0.011 rows=0 loops=1)
Filter: (lower((email)::text) ~~ concat('%', 'explain', '%'))
Rows Removed by Filter: 1

by email part count

Aggregate  (cost=10.53..10.54 rows=1 width=2088) (actual time=0.013..0.013 rows=1 loops=1) ->  Seq Scan on usr u  (cost=0.00..10.53 rows=1 width=2088) (actual time=0.012..0.012 rows=0 loops=1)
Filter: (lower((email)::text) ~~ concat('%', 'explain', '%'))
Rows Removed by Filter: 1

by name part

Seq Scan on usr u  (cost=0.00..10.53 rows=1 width=2088) (actual time=0.009..0.009 rows=0 oops=1)
Filter: (lower((name)::text) ~~ concat('%', 'explain', '%'))
Rows Removed by Filter: 1

by name part count

Aggregate  (cost=10.53..10.54 rows=1 width=2088) (actual time=0.021..0.022 rows=1 loops=1) ->  Seq Scan on usr u  (cost=0.00..10.53 rows=1 width=2088) (actual time=0.019..0.019 rows=0 loops=1)
Filter: (lower((name)::text) ~~ concat('%', 'explain', '%'))
Rows Removed by Filter: 1

[codenvy-ci]

Build success. https://ci.codenvycorp.com/job/che-pullrequests-build/2584/