[sqlite] Index with calculated value not covering?

[Wout Mertens]

sqlite> CREATE TABLE "history"("v" INTEGER PRIMARY KEY AUTOINCREMENT,
"type" TEXT, "data" JSON);
sqlite> CREATE INDEX "type_size" on history(type, length(data));
sqlite> explain query plan select type from history group by type;
QUERY PLAN
`--SCAN TABLE history USING COVERING INDEX type_size
sqlite> explain query plan select type, length(data) from history group by
type;
QUERY PLAN
`--SCAN TABLE history USING INDEX type_size

I would expect the latter query to use COVERING index. Is there a way to
hint this?

(I checked the actual opcodes and indeed it reads the table column and runs
length again)

Wout.
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