Merge pull request #5464 from EnterpriseDB/docs/pg_squeeze/lock-levels

Added information about lock levels to pg_squeeze docs

advocacy_docs/pg_extensions/pg_squeeze/using.mdx

@@ -3,9 +3,34 @@ title: Using pg_squeeze
 navTitle: Using
 ---
 
+Use `pg_squeeze` to remove unused space from a table and optionally sort tuples according to a particular index.
+
+## Understanding lock levels while using `pg_squeeze`
+
+While using `pg_squeeze`, the extension performs a series of actions, and some of these actions place a lock on the squeezed table, as described in the following steps. The table being squeezed is available for both read and write operations by other transactions most of the time. 
+
+When squeezing a table, the extension:
+
+1. Creates a transient table and copies the contents of the source table using the snapshot.
+
+    `pg_squeeze` holds an `ACCESS SHARE` lock on the source table during this step. 
+
+1. Builds indexes on the transient table.
+
+    `pg_squeeze` holds an `ACCESS SHARE` lock on the source table during this step. 
+
+1. Decodes and applies the concurrent changes that occurred on the source table while the initial load is in progress.
+
+1. Applies any concurrent changes that take place while waiting for the lock and swaps the storage of the transient and the source table.
+
+    `pg_squeeze` holds an `ACCESS EXCLUSIVE` lock for a short period during this step.
+
+1. Drops the transient table.
+
+
 ## Registering a table for regular processing
 
-First, ensure that your table has either a primary key or a unique constraint. This is necessary to process changes resulting from other transactions  while `pg_squeeze` is doing its work.
+Before using `pg_squeeze`, ensure that your table has either a primary key or a replica identity. This is necessary to process changes resulting from other transactions  while `pg_squeeze` is doing its work.
 
 To make the `pg_squeeze` extension aware of the table, you must insert a record into the `squeeze.tables` table. After it is added, table statistics are checked periodically. When the table meets the necessary criteria to be squeezed, a task is added to a queue. The tasks are processed sequentially, in the order they are created.