Select * from pg_stat_statements where query like '%optionB%' After no rows need changes, we can switch the columnsĪLTER /*optionB*/ TABLE PRU DROP COLUMN A ĪLTER /*optionB*/ TABLE PRU DROP COLUMN A1_CHANGED ĪLTER /*optionB*/ TABLE PRU RENAME A1 TO A SELECT COUNT(1) FROM PRU WHERE A1_CHANGED is null SELECT COUNT(1) FROM PRU WHERE A1_CHANGED=true To alter the owner, you must also be a direct or indirect member of the new owning role. To change a materialized view's schema, you must also have CREATE privilege on the new schema. You must own the materialized view to use ALTER MATERIALIZED VIEW.
#Postgres rename column update
UPDATE /*optionB*/ PRU SET A1=A::INTEGER, A1_CHANGED=true WHERE id IN (SELECT id FROM PRU WHERE A1_CHANGED is null limit 100000) ALTER MATERIALIZED VIEW changes various auxiliary properties of an existing materialized view. This sentence must be repeated multiple times until all rows were updated Update sentence with limit number or fows to update in single transaction However, its very convenient to be able to write scripts which modify DB structure which can be run again without first checking. ALTER TABLE t RENAME COLUMN IF EXISTS c1 TO c2.or anything like that. The best way to do this is to use multiple ALTER statements. postgresql - Rename column only if exists - Stack Overflow. ALTER TABLE cat ALTER COLUMN id TYPE varchar(50) RENAME id TO identity The above is wrong and will return an error. Trigger to take care of ongoing changes from the applicationsĮLSEIF (NEW.a is null and OLD.a is not null) THENĮLSEIF (NEW.a is not null and OLD.a is null) THEN the Simple ALTER Table Query to Change Data Type and Column Name in PostgreSQL No single ALTER statement in PostgreSQL would perform something like this. The advantages of doing in this way is that the customer has more control about the process, it can be executed during multiples hours/days.ĪLTER TABLE PRU ADD COLUMN A1 INTEGER, ADD COLUMN A1_CHANGED BOOLEAN This method is the easiest one, but could generate high contention due to required exclusive lock for the table that could generate errors in applications, most of them will require stop applications to perform this type of long running operations.Īnother approach to change the datatype of the column could be to add some extra columns, migrate the data to those columns and finally drop old column and rename new one. Select * from pg_stat_statements where query like '%optionA%' Second, provide name of the column that you want to rename after the RENAME COLUMN keywords. We could review stats from this command with following command: First, specify the name of the table that contains the column which you want to rename after the ALTER TABLE clause. Generate rows until 2M, repeating this sentence:ĪLTER /*optionA*/ TABLE PRU ALTER COLUMN A TYPE INTEGER USING A::INTEGER SELECT * FROM pg_stat_statements_reset() Supose table PRU with bigserial id column and column A, with integer data saved as Text that you want to change to Integer type: See the original author and article here.ĭue to performance and locking reasons, change datatype column can be a long-running operation.
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