We are seeing these "ERROR: unexpected chunk number 0 (expected 1) for toast value 1498303849 in pg_toast_10919630" in increasing numbers again¹. An observation is that they seem to only happen for tsvector fields. Here is an example sequence of queries for a record (we have more than a handful of these currently), which exhibits the problem. First we get two other fields, 'sequence' is large enough to be toast'ed: 2018-01-16 08:51:17.362 efam=# select id,sequence from efam.sequence where id = 164504550; Time: 1.150 ms No problem. Then we also fetch the tsvector field: 2018-01-16 08:51:27.773 efam=# select id,sequence,fts from efam.sequence where id = 164504550; ERROR: unexpected chunk number 0 (expected 1) for toast value 1498303849 in pg_toast_10919630 Time: 0.912 ms And we get the error. Getting the id and the tsvector: 2018-01-16 08:51:34.174 efam=# select id,fts from efam.sequence where id = 164504550; ERROR: unexpected chunk number 0 (expected 1) for toast value 1498303849 in pg_toast_10919630 Time: 6.138 ms gives the error. Just getting the tsvector: 2018-01-16 08:51:40.066 efam=# select fts from efam.sequence where id = 164504550; ERROR: unexpected chunk number 0 (expected 1) for toast value 1498303849 in pg_toast_10919630 Time: 1.805 ms Gives the error. Field definitions: id | integer | sequence | text | fts | tsvector | Maybe the observation that this only happens (for us) on tsvector rings a bell for someone? Best regards, Adam ¹ As reported back in June, 2017, starting here: https://www.postgresql.org/message-id/7pefuv53dl.fsf%40novozymes.com (I have to admit I never got around to trying to revert the commit Alvaro Herrera suggested we try without (https://www.postgresql.org/message-id/20170611033840.hruqadsk47qcdrqb%40alvherre.pgsql)) -- "No more than that, but very powerful all the Adam Sjøgren same; simple things are good." adsj@xxxxxxxxxxxxx