Upsert as (update test set info=$info,crt_time=$crt_time where id=$id returning *) When the same data item is updated, the first established session locks the record, whereas the session that is established later enters the waiting state. 3) With Syntax - Method 2Įnsure concurrency even if the table does not have a primary key or a unique constraint.Ĭreate table test(id int, info text, crt_time timestamp) 3.1) Data Inserted to Only One Session. When a nonexistent value is inserted, only one session has the successfully inserted value, whereas the other session returns a primary key constraint error. With upsert as (update test set info='test',crt_time=now() where id=1 returning *) insert into test select 1,'test',now() where not exists (select 1 from upsert where id=1) Replace the variables and perform a test. With upsert as (update test set info=$info,crt_time=$crt_time where id=$id returning *) insert into test select $id,$info,$crt_time where not exists (select 1 from upsert where id=$id) Update batch set info=var.info,crt_time=var.crt_time where id=var.id create table batch (id int primary key, info text, crt_time timestamp) Ĭreate or replace function merge_batch(VARIADIC i batch) To write data in batches, create variables as shown below. Test03=# select f_upsert(3,'hello',now()::timestamp) Test03=# select f_upsert(1,'digoal',now()::timestamp) Update test set info=$2,crt_time=$3 where id=$1 - insert into test values ($1,$2,$3) on conflict (id) do update set info=,crt_time=excluded.crt_time Insert into test (id,info,crt_time) values ($1,$2,$3) Update test set info=$2,crt_time=$3 where id=$1 1) Functions test03=# create or replace function f_upsert(int,text,timestamp) returns void as $$ Use different methods to meet the actual requirements. (2 rows) Upsert Usage Example for Versions Earlier Than 9.5 Test03=# insert into test values (2,'pu',now()) on conflict (id) do nothing Test03=# insert into test values (1,'pu',now()) on conflict (id) do nothing test03=# insert into test values (1,'hello digoal',now()) on conflict (id) do nothing Step 2) If the data does not exist, insert it. Test03=# insert into test values (1,'hello digoal',now()) on conflict (id) do update set info=,crt_time=excluded.crt_time test03=# insert into test values (1,'test',now()) on conflict (id) do update set info=,crt_time=excluded.crt_time Step 1) If a table does not exist, insert it. Upsert Usage Example for Versions Later Than 9.5Įxecute the following command to create a test table with one field as the unique key or primary key.Ĭreate table test(id int primary key, info text, crt_time timestamp) ) |įor versions earlier than PostgreSQL 9.5, use functions or the with syntax to implement functions similar to upsert. The syntax for the same is as follows: Command: INSERT When a constraint error occurs during data insertion, data insertion is rolled back or changed to update. Where not exists (select * from Test1 as t where t.key = v.key and t.value = v.Upsert (INSERT ON CONFLICT DO) is a new function of PostgreSQL 9.5. Unless one or both of the "key"/"value" pair can be null. If the row does not exist it will return the inserted one else the existing one.īTW, if the pair "key"/"value" makes it unique then it is the primary key, and there is no need for an id column. To return the row if it already exists with s as ( Yes there is returning INSERT INTO tag ("key", "value")
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