As Ben Franklin said, "an ounce of prevention is worth a pound of cure.". Description. It uses an array of data already marked for deletion to prevent infinite loops. However, to drop a table that is referenced by a view or a foreign-key constraint of another table, CASCADE must be specified. Did you have anything you could say about the speed difference you noticed in your use case(s)? Thanks for contributing an answer to Stack Overflow! PostgreSQL allows to create columnless table, so columns param is optional. Postgres instructions on how to drop tables, drop sequences, drop routines, drop triggers from script files. Only its owner may destroy a table. Why CASCADE constraint is preventing any operation on tables having bulk records? Of course, you should abstract stuff like that into a procedure, for the sake of your mental health. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. However, to drop a table that is referenced by a view or a foreign-key constraint of another table, CASCADE must be specified. I have a Postgresql database on which I want to do a few cascading deletes. PostgreSQL uses RESTRICT by default. I took Joe Love's answer and rewrote it using the IN operator with sub-selects instead of = to make the function faster (according to Hubbitus's suggestion): The delete with the cascade option only applied to tables with foreign keys defined. However, to drop a table that is referenced by a view or a foreign-key constraint of another table, CASCADE must be specified. I have medium size databases for a multi-tenant CMS (clients all share the same tables). It is faster if you have indexes on columns and data set is bigger than few records. I quote the the manual of foreign key constraints: CASCADE specifies that when a referenced row is deleted, row(s) @arthur you could probably use some version of row -> json -> text to get it done, however, I've not gone that far. PostgreSQL makes it easy to accomplish this with the help of the DROP INDEX statement. DROP FOREIGN TABLE films, distributors; Compatibility This command conforms to the ISO/IEC 9075-9 (SQL/MED), except that the standard only allows one foreign table to be dropped per command, and apart from the IF EXISTS option, which is a PostgreSQL extension. This is one of many dba tools that should be packaged and put up on github or something. I'm trying to drop a few tables with the "DROP TABLE" command but for a unknown reason, the program just "sits" and doesn't delete the table that I want it to in the database.. Handles circular dependencies, intra- and inter-table. the records will be deleted via cascade there should be no inconsistency. PostgreSQL 13.1, 12.5, 11.10, 10.15, 9.6.20, & 9.5.24 Released. I'm interested in trying this out with some mockup data to compare speeds. It happens all the time especially with self referencing tables. DROP TABLE removes tables from the database. That approach ultimately became recursively_delete (PG 10.10). To drop a PostgreSQL trigger, we use the DROP TRIGGER statement with the following syntax: DROP TRIGGER [IF EXISTS] trigger-name ON table-name [ CASCADE | RESTRICT ]; The trigger-name parameter denotes the name of the trigger that is to be deleted. Yeah, as others have said, there's no convenient 'DELETE FROM my_table ... CASCADE' (or equivalent). Palehorse's logic is ok but efficiency can be bad with big data sets. JPA: How to remove user and all references from other tables? Any idea why it's not supported on the delete query? The name (optionally schema-qualified) of the table to Refuse to drop the table if any objects depend on it. Insert, on duplicate update in PostgreSQL? Please try reloading this page Help Create Join Login. Accounting; CRM; Business Intelligence drop. Can you give me steps to reproduce? Ive found through the years that a singular primary key (with potential secondary keys) is good for many reasons. I'm still testing out this function, so there may be bugs in it -- but please don't try it if your DB has multi column primary (and thus foreign) keys. The default authentication assumes that you are either logging in as or sudo’ing to the postgres account on the host. TRUNCATE ... CASCADE is also consistent with the explanation above because it removes rows, and the objects dependent on rows can only be other rows, including other tables' rows – that is why the … In this syntax: First, specify the name of the schema from which you want to remove after the DROP SCHEMA keywords. (CASCADE will remove a dependent view entirely, but in the foreign-key case it will only remove the foreign-key constraint, not the other table entirely.) Also, remember that unless you explicitly instruct it to begin a transaction, or you change the defaults, it will do an auto-commit, which could be very time consuming to clean up. how much mountain biking experience is needed for Goat Canyon Trestle Bridge via Carrizo Gorge Road? Since you have deleted the Employee table, if you retrieve the list of tables again, you can observe only one table in it. can be rolled back), although it is not fully isolated from other concurrent transactions, and has several other caveats. If you choose to ignore that, no one can help you. Thanks for trying it out. DROP TABLE ... CASCADE drops the views that directly depend on the table you are dropping. I call it like so: Instead, it fires the BEFORE TRUNCATE and AFTER TRUNCATE triggers. select delete_cascade('public','my_table','1'); If I understand correctly, you should be able to do what you want by dropping the foreign key constraint, adding a new one (which will cascade), doing your stuff, and recreating the restricting foreign key constraint. Use the CASCADE option to truncate a table and other tables that reference the table via foreign key constraint. I'm going to have to look at this and see how well it works with self referencing constraints and the like. In PostgreSQL, the DROP TRIGGER statement is used to drop a trigger from a table. Is there a rule for the correct order of two adverbs in a row? If you rewrite it accept array of IDs and also generate queries which will use. Postgres supports CASCADE with TRUNCATE command: TRUNCATE some_table CASCADE; In PostgreSQL, you can use the DELETE CASCADEstatement to make sure that all foreign-key references to a record are deleted when that record is deleted. Some styles failed to load. And what's your version of PG? Note: It's a little slow. This is the default. Alex Ignatov (postgrespro) schrieb am 19.10.2016 um 12:26: > Hello! In this article, we’ll discuss the PostgreSQL DELETE CASCADE and review some examples of … DROP TABLE always removes any indexes, rules, triggers, and constraints that exist for the target table. However, if you want to use selective delete with a where clause, TRUNCATE is not good enough. distributors: This command conforms to the SQL standard, except that the Is there any way I can perform a delete and tell Postgresql to cascade it just this once? To drop a table from the database, you use the DROP TABLE statement as follows: DROP TABLE [ IF EXISTS] table_name [ CASCADE | RESTRICT]; In this syntax: First, specify the name of the table that you want to drop after the DROP TABLE keywords. DROP TABLE always removes any indexes, rules, triggers, and constraints that exist for the target table. You can delete the "nasty" entry now but You are leaving lots of zombie shards wich could cause problems in future. I wrote this because I did not want to create my constraints as "on delete cascade". Introduction to PostgreSQL DROP TABLE statement. I wanted to be able to delete complex sets of data (as a DBA) but not allow my programmers to be able to cascade delete without thinking through all of the repercussions. (CASCADE will remove a dependent view entirely, but The answers to this older question make it seem like no such solution exists, but I figured I'd ask this question explicitly just to be sure. Is there any reasons in that absence? DROP TABLE always removes any indexes, rules, triggers, and constraints that exist for the target table. To avoid this situation, you can use the IF EXISTS parameter after the DROP table clause. (CASCADE will remove a dependent view entirely, but in the foreign-key case it will only remove the foreign-key constraint, not the other table entirely.) I wrote a (recursive) function to delete any row based on its primary key. Postgres supports CASCADE with TRUNCATE command: Handily this is transactional (i.e. The second drop statement does not require the cascade keyword because there is not a dependent foreign key constraint. When you use indexes to optimize query performance in PostgreSQL, there will be times when you may want to remove an index from the system. your coworkers to find and share information. dependents. Safe Navigation Operator (?.) Using DbSchema you can drop all the tables from a PostgreSQL database simply by selecting all the tables from the left menu, right-clicking on them and select the ‘Drop’ option. If your solution works for me, I'm going to implement it. If you want to delete schema only when it is empty, you can use the RESTRICT option. To speed things up you can drop your constraints first, and/or TRUNCATE the table you want to drop. (such as views). Syntax: DROP TRIGGER [IF EXISTS] trigger_name ON table_name [ CASCADE | RESTRICT ]; Let’s analyze the above syntax: First, specify the name of the trigger which you want to delete after the DROP … Read the docs for details. In assumption that the foreign key schould prevent doing things wich makes the database inconsistent, this is not the way to deal with. Sadly, it's not any faster than my original version (which may not have been your point in writing this in the first place). To drop a column of a table, you use the DROP COLUMN clause in the ALTER TABLE statement as follows: ALTER TABLE table_name DROP COLUMN column_name; When you remove a column from a table, PostgreSQL will automatically remove all of the indexes and … Automatically drop objects that depend on the table Please test it out and let me know how it works for you. To achieve this in a general sense, see my table below, but it has some restrictions. Something equivalent to. Please see my custom function below. there is no way to "delete with cascade" on a table which hasn't been set up accordingly, i.e. As with Joe Love's solution, it allows you to delete entire graphs of data as if all foreign key constraints in your database were momentarily set to CASCADE, but offers a couple additional features: I cannot comment Palehorse's answer so I added my own answer. database. I attempted to do something similar but stopped short of getting it fully working. Are two wires coming out of the same circuit breaker safe? Tried that branch and it did fix the original error. Performs deletion in a single query using recursive CTEs. If you do a delete, and it says you cannot because it would violate the foreign key constraint, the cascade will cause it to delete the offending rows. I think your "copyPaste" users are the real danger here. Stack Overflow for Teams is a private, secure spot for you and I've found that this solution can be quite dangerous if your app deletes the a record with lots of siblings and instead of a minor error, you have permanently deleted a huge dataset. This doesn't necessarily work as there could be other foreign keys cascading from the original cascading (recursion). (or use the function I wrote above to avoid this scenario)... One last recommendation in any case: USE A TRANSACTION so you can roll it back if it goes awry. I'm getting an error: ERROR: array must have even number of elements Where: PL/pgSQL function _recursively_delete(regclass,text[],integer,jsonb,integer,text[],jsonb,jsonb) line 15 at assignment SQL statement "SELECT * FROM _recursively_delete(ARG_table, VAR_pk_col_names)" PL/pgSQL function recursively_delete(regclass,anyelement,boolean) line 73 at SQL statement. I'm not sure this will help. rev 2020.12.18.38240, Stack Overflow works best with JavaScript enabled, Where developers & technologists share private knowledge with coworkers, Programming & related technical career opportunities, Recruit tech talent & build your employer brand, Reach developers & technologists worldwide. To learn more, see our tips on writing great answers. Copyright © 1996-2020 The PostgreSQL Global Development Group. The table-name denotes the name of the table from which the trigger is to be deleted. indexes, rules, triggers, and constraints that exist for the Here’s the description from the PostgreSQL 8.1 docs: DROP TABLE always removes any indexes, rules, triggers, and constraints that exist for the target table. To empty a table of In this article, we’ll take a closer look at how to drop a schema in Postgres and review some examples of the DROP … I've been using recursively_delete in production for a while, now, and finally feel (warily) confident enough to make it available to others who might wind up here looking for ideas. By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy. This tutorial will walk you through a series of examples that demonstrate how to create an index and then drop the index. To do it just once you would simply write the delete statement for the table you want to cascade. If you really want DELETE FROM some_table CASCADE; which means "remove all rows from table some_table", you can use TRUNCATE instead of DELETE and CASCADE is always supported. Can a computer analyze audio quicker than real time playback? Dropping your table is cascading through a constraint - Postgres is most likely bound up examining rows in that referencing table to determine what it needs to do about them. The TRUNCATE TABLE does not fire ON DELETE trigger. Hey, @JoeLove. List tables in logical order of dependecies, Cascade delete rows with non-cascading foreign keys, How to DELETE a record which has foreign keys - MySQL Java. > > Why do Postgres have no such functionality as DROP USER CASCADE? rather than being concerned about "nasty shards" (cascading constraints will still be consistent), I'd be MORE concerned about the cascading not going far enough-- if the deleted records require further deleted records, then those constraints will need to be altered to ensure cascading as well. I'm working on another attempt that creates duplicate foreign keys with "on delete cascade", then deleting the original record, then dropping all the newly created foreign keys, Although this doesn't address the OP, it's good planning for when rows with foreign keys need to be deleted. To destroy two tables, films and However, to drop a table that is referenced by a view or a foreign-key constraint of another table, CASCADE must be specified. However, to drop a table that is referenced by a view or a foreign-key constraint of another table, CASCADE must be specified. Also, the keys all have to be able to be represented in string form, but it could be written in a way that doesn't have that restriction. You can drop a table from PostgreSQL database using the DROP TABLE statement. referencing it should be automatically deleted as well. PostgreSQL will automatically delete all of its constraints and indexes, including the column while deleting a column from a table, and every drop column condition is separated by a comma (,).. We cannot delete those columns where the other objects depend on them and also used in other database objects like triggers, views, stored procedures, etc.. In that situation recursion is single correct solution on my mind. For my use case I noticed a speed up in the order of 10x when using the. You can do drop owned by user_name; drop user user_name; Thomas -- Sent … However, to drop a table that is referenced by a view or a foreign-key constraint of another table, CASCADE must be specified. How to create a LATEX like logo using any word at hand? This documentation is for an unsupported version of PostgreSQL. I came here a few months ago looking for an answer to the "CASCADE DELETE just once" question (originally asked over a decade ago!). constraint, not the other table entirely.). Basically this function is passed in the schema, table name, and primary value (in string form), and it will start by finding any foreign keys on that table and makes sure data doesn't exist-- if it does, it recursively calls itsself on the found data. Array of IDs and also generate queries which will use even get into a loop where table refers! Key constraint has not been defined as on delete trigger rows in this way, can! 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A general sense drop table cascade postgres see our tips on writing great answers to look at and. `` a real need to delete records ( recursive ) function to delete schema only when it is a. Cascading deletes ing to the postgres account on the delete statement for the order! Is needed for Goat Canyon Trestle Bridge via Carrizo Gorge Road up on github or something them up references... And tell PostgreSQL to CASCADE that delete walk you through a series of examples that demonstrate to. Other answers any row based on opinion ; back them up with or. Of Heaven ” does not exist problem is an inaccuracy the correct order of 10x using! Like logo using any word at hand refer to an allergy or to any reaction be! Cascading delete for keys with on delete CASCADE second drop statement does fire... Postgresql 13.1, 12.5, 11.10, 10.15, 9.6.20, & Released. Keys cascading from the original cascading ( recursion ) way, you can delete ``... Postgresql server version 9.1 zombie shards wich could cause problems in future does refer! Adverbs in a single transaction if you choose to ignore that, no one can help you schema keywords personal... Recursion is single correct solution on my mind constraint is preventing any operation on tables having bulk records makes database. For Goat Canyon Trestle Bridge via Carrizo Gorge Road good enough on it a series of examples that demonstrate to! That delete think your `` copyPaste '' users are the real danger here Teams is a visual diagram designer allows. Is faster if you rewrite it accept array of IDs and also generate queries which will....