dblink_build_sql_update(text relname,
int2vector primary_key_attnums,
integer num_primary_key_atts,
text[] src_pk_att_vals_array,
text[] tgt_pk_att_vals_array) returns textdblink_build_sql_update can be
useful in doing selective replication of a local table to a remote
database. It selects a row from the local table based on primary
key, and then builds a SQL UPDATE command
that will duplicate that row, but with the primary key values
replaced by the values in the last argument. (To make an exact copy
of the row, just specify the same values for the last two
arguments.) The UPDATE command always
assigns all fields of the row — the main difference between this
and dblink_build_sql_insert is that
it's assumed that the target row already exists in the remote
table.
Name of a local relation, for example foo or myschema.mytab. Include double quotes if the name is mixed-case or contains special characters, for example "FooBar"; without quotes, the string will be folded to lower case.
Attribute numbers (1-based) of the primary key fields, for example 1 2.
The number of primary key fields.
Values of the primary key fields to be used to look up the local tuple. Each field is represented in text form. An error is thrown if there is no local row with these primary key values.
Values of the primary key fields to be placed in the resulting UPDATE command. Each field is represented in text form.
As of PostgreSQL 9.0, the attribute numbers in primary_key_attnums are interpreted as logical column numbers, corresponding to the column's position in SELECT * FROM relname. Previous versions interpreted the numbers as physical column positions. There is a difference if any column(s) to the left of the indicated column have been dropped during the lifetime of the table.