Retrieve large blob from Android sqlite database

Question

I stored chunks of binary data (protobufs) in the sqlite database of an Android app without realizing that Android\'s Cursor can only hold a maximum of 1MB of d

Answer 1

You can read large blobs in pieces. First find out which ones need this treatment:

SELECT id, length(blobcolumn) FROM mytable WHERE length(blobcolumn) > 1000000

and then read chunks with substr:

SELECT substr(blobcolumn,       1, 1000000) FROM mytable WHERE id = 123
SELECT substr(blobcolumn, 1000001, 1000000) FROM mytable WHERE id = 123
...

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You could also compile your own copy of SQLite and access either the BLOB stream I/O functions or the normal query functions of the C API with the NDK, but that would be too complex in this case.