From 9f414938ba7ee7daa5469ff4cf08057416e804e6 Mon Sep 17 00:00:00 2001 From: Javier Goizueta Date: Mon, 1 Jul 2019 16:41:40 +0200 Subject: [PATCH] Document CDB_SyncTable --- doc/CDB_SyncTable.md | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 doc/CDB_SyncTable.md diff --git a/doc/CDB_SyncTable.md b/doc/CDB_SyncTable.md new file mode 100644 index 0000000..7069747 --- /dev/null +++ b/doc/CDB_SyncTable.md @@ -0,0 +1,42 @@ +Synchronize two tables. This function will synchronize a *destination* table with a *source* table. +The idea is that the *destination* is a replica of *source* and *source* has been subject to +modifications that are to be applied to *destination*. + +This will be achieved by deleting the rows in the destination not present +in the source, inserting rows of the source not in the destination and updating modified rows. +If the destination table does not exist it will be created and all the rows of the source inserted into it. + +Both tables must have a consistent `cartodb_id` primary key column which will be used to match +the source and destination rows. + +Note that both tables do not necessaryly become identical after the synchronization, since additional columns +may have been added to the destination; those columns will not be altered by the synchronization. + +In addition some source columns may be skipped by listing them in the optional last argument; such columns +will not be updated in the destination, so if they are present in it their values won't be altered. + + +#### Using the function + +Import some data using COPY FROM into a temporary table, then synchronize a table with the data and +finally delete the temporary table. This could be used import and update some data periodically while +allowing to add columns to the data that will be preserved across updates. + + +```sql +CREATE tmp_pois(cartodb_id int, name text, type text, longitude double precision, latitude double precision); +COPY tmp_pois FROM '/tmp/pois.csv'; +SELECT CDB_SyncTable('tmp_pois', 'public', 'pois'); +DROP TABLE tmp_pois; +``` + +#### Arguments + +``` +CDB_SyncTable(src_table, dst_schema, dst_table, skip_cols) +``` + +* **src_table** REGCLASS the source data for the synchronization +* **dst_scgena** REGNAMESPACE the destination schema +* **dst_table** NAME the destination table to be updated +* **skip_cols** NAME[] an array of column names, empty by default, which will be skipped