Windows SuperFetch Format

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Note that the following format specification are incomplete.

SuperFetch DB files

The Ag*.db files are of the SuperFetch file format. E.g.

AgAppLaunch.db
AgCx_SC*.db
AgGlFaultHistory.db
AgGlFgAppHistory.db
AgGlGlobalHistory.db
AgGlUAD_%SID%.db
AgGlUAD_P_%SID%.db
AgRobust.db

The SuperFetch DB files can be stored in uncompressed or compressed form, where different version of Windows use different compression methods:

  • Compressed SuperFetch DB - MEM file format; Windows Vista and 7
  • Compressed SuperFetch DB - MAM file format; Windows 8

Compressed SuperFetch DB - MEM file format

The MEM file consists of:

  • file header
  • compressed blocks

File header

The file header is 84 bytes of size and consists of:

Offset Size Value Description
0 4 "MEMO" (0x4d, 0x45, 0x4d, 0x4f)
"MEM0" (0x4d, 0x45, 0x4d, 0x30)
Signature
4 4 Uncompressed (total) data size

Where:

  • "MEMO" (0x4d, 0x45, 0x4d, 0x4f) is used on Windows Vista and uses the LZNT1 compression method
  • "MEM0" (0x4d, 0x45, 0x4d, 0x30) is used on Windows 7 and uses the LZXPRESS Huffman compression method

Compressed blocks

The file header is followed by compressed blocks:

Offset Size Value Description
0 4 Compressed data size
4 ... Compressed data

The uncompressed block size is 65536 (0x10000) or the remaining uncompressed data size for the last block.

Compressed SuperFetch DB - MAM file format

On Windows 8 (seen on 8.1) the MEM file format seem to have been replaced by the MAM file format.

File header

TODO

Offset Size Value Description
0 4 "MAM\x84" (0x4d, 0x41, 0x4d, 0x84) Signature

Compressed blocks

TODO

Uncompressed SuperFetch DB format

TODO

TRX files

The Ag*.db.trx files are of the TRX file format. E.g.

AgCx_SC*.db.trx

Note that the following format specification is incomplete.

File header

The file header is variable of size and consists of:

Offset Size Value Description
0 4 1 Unknown (Version?)
4 4 Unknown
8 4 File size
12 4 Maximum number of records (of the record offsets array)
16 4 Number of records
20 ... Record offsets array, where the record offset is a 32-bit integer. Unused record offset are set to 0.

Record

TODO describe

See Also

External Links