NOT EXISTS stories( id bigserial NOT NULL, create_date timestamp without time zone NOT NULL, num_views bigint NOT NULL, title text NOT NULL, body text NOT NULL, fulltext tsvector, user_id bigint, PRIMARY KEY (id),CONSTRAINT user_id_fk FOREIGN KEY (user_id)REF...
user_id bigint, PRIMARY KEY (id), CONSTRAINT user_id_fk FOREIGN KEY (user_id) REFERENCES users (id) MATCH SIMPLE ON UPDATE NO ACTION ON DELETE NO ACTION NOT VALID ) ; CREATE INDEX str_bt_idx ON stories USING btree (create_date ASC NULLS LAST, num_views ASC NULLS LAST, user_id AS...
A foreign-key constraint ensures that each row in the referencing table matches a row in the referenced table. Therefore, if the referencing table is a member of a replication set, the referenced table must also be a member of the same replication set. ...
CONSTRAINT user_id_fk FOREIGN KEY (user_id) REFERENCES users (id) MATCH SIMPLE ON UPDATE NO ACTION ON DELETE NO ACTION NOT VALID ) ; CREATE INDEX str_bt_idx ON stories USING btree (create_date ASC NULLS LAST, num_views ASC NULLS LAST, user_id ASC NULLS LAST) ; CREATE INDEX fulltext...
多列组成唯一约束CREATETABLEexample ( ainteger, binteger, cinteger,UNIQUE(a, c) );CREATETABLEproducts ( product_nointegerCONSTRAINTmust_be_differentUNIQUE, nametext, price numeric ); 主键CREATETABLEproducts ( product_nointegerUNIQUENOTNULL,
We discussed some theory, and considered a realistic example by constructing a work schedule for a small store. In this follow-up article, we’ll now take our understanding of constraint programming, and apply it to a real-world example: Selecting optimal indexes in Postgres. The model ...
user_idbigint,PRIMARYKEY (id),CONSTRAINTuser_id_fkFOREIGNKEY (user_id)REFERENCESusers (id)MATCHSIMPLEONUPDATENOACTIONONDELETENOACTIONNOTVALID ) ;CREATEINDEX str_bt_idxONstoriesUSINGbtree (create_dateASCNULLSLAST, num_viewsASCNULLSLAST, user_idASCNULLSLAST) ...
Foreign Key Constraint Conflicts Conflicts between a remote transaction being applied and existing local data can also occur forFOREIGN KEYconstraints (FKs). BDR applies changes withsession_replication_role = 'replica', so foreign keys arenotre-checked when applying changes. In an active/active enviro...
Conflict resolution can only use one index at a time so conflicting rows may ERROR if a row satisfies the PRIMARY KEY but violates a UNIQUE constraint on the downstream side. This will stop replication until the downstream table is modified to remove the violation. It's fine to have extra ...
The fact that an insert will cause an exclusive lock on the referenced row for a foreign key constraint is a severe performance restriction anyway, because no other concurrent transaction can insert a row in any other table referencing the same row... the only way to work this around was ...