How to drop index on a particular table. According to the syntax as
DROP INDEX <INDEX_NAME>
It will delete the index on that particular schema.
My requirement is I want to create an index named I9 on all the table under a particular schema. For example these are the list of tables under schema s1 (t1,t2,t3,t4,t5,t6).I have created I9 index on all the tables.
Now I want to delete the index only on table t3.
Can some one please let me know the syntax for this.
Related
Created index on partition table movies.actors_2010(name) with schemaname movies.actors_2010_name_idx
CREATE INDEX CONCURRENTLY "movies.actors_2010_name_idx" ON movies.actors_2010(name);
Now when I try to drop the index, output shows index doesn't exist and index remain same, can't drop it.
drop index IF EXISTS movies.actors_2010_name_idx;
Any suggestions are helpful.
The problem appears to be that you quoted the identifier "movies.actors_2010_name_idx". That created an index with a . in the name, not an index named "actors_2010_name_idx" in the movies schema. To do that, you should have used
CREATE INDEX CONCURRENTLY "movies"."actors_2010_name_idx" ON "movies"."actors_2010"(name);
or
CREATE INDEX CONCURRENTLY movies.actors_2010_name_idx ON movies.actors_2010(name);
Now to do delete the index with the broken name, you'd use
DROP INDEX IF EXISTS "movies.actors_2010_name_idx";
or possibly
DROP INDEX IF EXISTS "movies"."movies.actors_2010_name_idx";
I have a Postgres table named: services, and it has columns called id, mac_addr, dns_name, hash, and it is partitioned based on mac_addr, so the partition tables names look like: services_3eeeea123e3 and so on. And there are around 20K partition based on mac_addrs
Q1: there was no index created when the tables were created. so now, when I am trying to add an index CREATE INDEX idx_services_id on services (id), it throws an error ERROR: cannot create an index on partitioned table "services"
But I am able to add indexes to individual partitioned tables CREATE INDEX idx_services_3eeeea123e3 on services_3eeeea123e3 (id).
So do I have to create an index on each partition table now? Is there a way to create an index on the base table(services) itself, which will automatically create an index on each partition table?
Q2: When I run a select query, it is fast when I use the direct partition table; however, using the base table is very slow. Any idea what could be the reason.
Fast: SELECT id, dns_name, hash from services_3eeeea123e3 where id='123232'
very slow: SELECT id,dns_name, hash from services where mac_addr='3eeeea123e3' and id='123232'
I have a table MAIN_SCHEMA.TEST in which I created a Index on a column CHECK_ID.
CHECK_ID is also a FOREIGN_KEY constraint in TEST table.
This table contains only 50 records.
By Mistake the index got created in Default schema DEFAULT_SCHEMA.CHECK_ID_IDX.
CREATE INDEX DEFAULT_SCHEMA.CHECK_ID_IDX(CHECK_ID ASC);
So I am trying to drop this index but the drop query gets stuck for long time.
DROP INDEX DEFAULT_SCHEMA.CHECK_ID_IDX.
there are no locks on this table when I checked.
Instead of dropping and recreating the index with the right schema, could you just try to RENAME the index? It requires the existing SCHEMA.NAME pair together with the new as input. It will not move any data, but just update the metadata.
is there automatic index in Postgresql or need users to create index explicitly? if there is automatic index, how can I view it? thanks.
An index on the primary key and unique constraints will be made automatically. Use CREATE INDEX to make more indexes. To view existing database structure including the indexes, use \d table.
A quick example of generating an index would be:
CREATE INDEX unique_index_name ON table (column);
You can create an index on multiple columns:
CREATE INDEX unique_index_name ON table (column1, column2, column3);
Or a partial index which will only exist when conditions are met:
CREATE INDEX unique_index_name ON table (column) WHERE column > 0;
There is a lot more you can do with them, but that is for the documentation (linked above) to tell you. Also, if you create an index on a production database, use CREATE INDEX CONCURRENTLY (it will take longer, but not lock out new writes to the table). Let me know if you have any other questions.
Update:
If you want to view indexes with pure SQL, look at the pg_catalog.pg_indexes table:
SELECT *
FROM pg_catalog.pg_indexes
WHERE schemaname='public'
AND tablename='table';
How to create indexes on MQT(materialized query table) in Db2? I haven't found this information in documentation? Is index creation syntax the same as for common tables?
After you create your MQT you have to refresh the table before you can create indexes. However, at this point it's exactly the same as creating indexes on a normal table.
There are some limitations on what type of indexes you can create on an MQT. For example, it cannot be a unique index.