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    <p>If you are generating the values on the fly using phyton, you could:</p> <ol> <li>Create a buffer containing a single <code>INSERT</code> statement</li> <li>Start a transaction</li> <li>Create a temporary table and perform the <code>INSERT</code> statement in your buffer</li> <li>Perform an <code>UPDATE ... FROM</code></li> <li>Commit the transaction, discarding the temporary table.</li> </ol> <p>The <code>UPDATE</code> statement will look like this (assuming there is a table <code>new_values</code> containing those new values you need to update):</p> <pre><code>UPDATE app_post AS a SET text_location = n.text_location FROM new_values AS n WHERE a.id = n.id </code></pre> <p>Don't forget to define the columns <code>id</code> as <strong>PRIMARY KEY</strong> or create an index on them.</p> <hr> <p><strong>EDIT</strong> : Since you are experiencing very slow performance, another workaround could be to recreate the whole table. The following idea assumes you don't have any <code>FOREIGN KEY</code> constraint applied to <code>app_post</code> table, as you have shown in your initial post.</p> <pre><code>-- Begin the Transaction BEGIN; -- Create a temporary table to hold the new values CREATE TEMPORARY TABLE temp_update_values ( id integer PRIMARY KEY, text_location integer ) ON COMMIT DROP; -- Populate it INSERT INTO temp_update_values (id, text_location) VALUES (1, 123), (2, 456) /* ... #5000 total */ ; -- Create a temporary table merging the existing "app_post" and "temp_update_values" CREATE TEMPORARY TABLE temp_new_app_post ON COMMIT DROP AS SELECT a.id, COALESCE(n.text_location, a.text_location) AS text_location, a.title FROM app_post AS a LEFT JOIN temp_update_values AS n ON a.id = n.id; -- Empty the existing "app_post" TRUNCATE TABLE app_post; -- Repopulate "app_post" table INSERT INTO app_post (id, text_location, title) SELECT id, text_location, title FROM temp_new_app_post; -- Commit the Transaction COMMIT; </code></pre> <p>If there are any <code>FOREIGN KEY</code> constraint, you should take care of them, dropping them before TRUNCATING the <code>app_post</code> table, and re-creating them after it's been repopulated.</p>
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    1. POHow to efficiently update postgres using a tuple of the PK and a value?
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    1. POHow to efficiently update postgres using a tuple of the PK and a value?
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    1. COThanks! do I need to use Begin to start the transaction?
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    2. COMaybe this is just slow whatever way I do it, but to run the update from new_values to app_post is taking 188seconds (and I have 4M posts to run through, so looking at almost a week). I ran the code above, and here is the explain analyze: https://code.stypi.com/znlqgrql
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    3. COAbout the transaction, yes, you must use `BEGIN` before the temporary table creation, and `COMMIT` after the update. About the speed, it's definitely too much time. You don't have any triggers on the `app_post` table? The *fastest* way would then be to create a new table, this could be plain easy, or tricky depending on your actual `FOREIGN KEYS`. I'll update the answer.
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