On Monday, July 15, 2024, sud &lt;<a href="mailto:suds1434@gmail.com">suds1434@gmail.com</a>&gt; wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div dir="ltr"><br></div><div class="gmail_quote"><div dir="ltr" class="gmail_attr">However even with &quot;vacuum full&quot;, the old rows will be removed completely from the storage , but the new rows will always be there with the &#39;dropped&#39; column still existing under the hood along with the table storage,  with just carrying &quot;null&quot; values in it. […] Is this understanding correct?<br></div></div></div></blockquote><div><br></div><div>No.  The table rewrite process involves creating new tuples that exactly conform to the current row specification.  The potentially non-null data present in live tuples for columns that have been dropped are not copied into the newly constructed tuples.</div><div><br></div><div><a href="https://github.com/postgres/postgres/blob/d2b74882cab84b9f4fdce0f2f32e892ba9164f5c/src/backend/access/heap/heapam_handler.c#L2499">https://github.com/postgres/postgres/blob/d2b74882cab84b9f4fdce0f2f32e892ba9164f5c/src/backend/access/heap/heapam_handler.c#L2499</a><br></div><div><br></div><div>David J. </div>