Post your solutions to the Apr 8 In-Class Exercise to this thread.

Best,

Chris

not done yet <T1, X , 6, 8>

• X not in disk

<C0MMIT T1> <FLUSH LOG> <START DUMP> <START CKPT (T2)> <T2, Y, 10, 5 > <END CKPT> -X->archive -Y->archive <END DUMP>

maybe this?

<T1, X, 6, 8> <COMMIT (T1)> <FLUSH LOG> <START DUMP> <START CHECKPOINT (T2)> <T2, Y, 10, 5> <COMMIT (T2)> <FLUSH LOG>

• db copies X=8 to disk
• db copies Y=5 to disk

<END CHECKPOINT>

• X=8 is copied to archive
• Y=5 is copied to archive

<END DUMP>

• copy over log records from the <START DUMP> to the <END DUMP> to the archive
• old logs in archive before the <START CHECKPOINT> are thrown away

<T1, X, 6, 8> <T1, Commit> <T2, Y, 10, 5> On disk: X = 6, Y = 10 <Start Dump> <Start Checkpoint (T2)> Dirty buffers written to disk On disk: X = 8, Y = 5 <End Checkpoint (T2)> database copies X as 8 database copies Y as 5 <End Dump>

in archive X = 8, Y = 5 log file before <Start T2> thrown out

<T1, X,6,8> <Commit T1> Memory X=8, Y=10 <T2, Y, 10, 5> <START DUMP> <START CKPT> write to disk, disk x = 6, disk y = 10 Memory Y = 5, X = 8 Disk x = 6, y = 10 <END CKPT> Archive Memory X = 8, Y= 10

<FLUSH LOG> <END DUMP>

<T1, X, 6, 8>

<COMMIT T1>

The new value of X is not on disk

X=8 is in memory

<T2, Y, 10, 5>

<START DUMP>

<START CHECKPOINT T2>

T2 is not on disk or memory

<FLUSH LOG>

T1 is stored on disk as X=8

T2 could be in a dirty block so it might be in disk

<END CHECKPOINT T2>

X=8 & Y=5 are moved to the archive

<END DUMP>

Logs from start checkpoint until end dump are preserved in the archive

<T1, X, 6, 8>

<COMMIT T1>

X = 8 in memory, X = 6 on disk still

<FLUSH LOGS>

<START DUMP>

<START CKPT T2>

<T2, Y, 10, 5>

<FLUSH LOGS>

<END CKPT T2>

<END DUMP>

T2 not committed so we lost it

<T1, X, 6, 8>

<COMMIT T1>

<START DUMP>

<T2, Y, 10, 5>

<FLUSH LOG>

<START CKPT (T2)>

<COMMIT T2>

<FLUSH LOG>

<END CKPT>

• X=8 is in memory and never on disk
• Y=5 is in memory and never on disk
• Archive <T1, X, 6, 8>
• Archive <T2, Y, 10, 5>

<END DUMP>

<T1, X, 6, 8> <COMMIT (T1)> -X=8 in memory, X=6 on disk <FLUSH LOG> <T2, Y, 10, 5> <START DUMP> <START CHECKPOINT(T2)> <COMMIT (T2)> <FLUSH LOG> <END CHECKPOINT> -X=8 and Y=5 copied to archive <END DUMP> -old log records are dumped but logs between start checkpoint and end dump are preserved in the archive

<T1, X, 6, 8> <COMMIT T1> new value of X is not on disk X=8 is in memory <FLUSH LOG> <START DUMP> <START CHECKPOINT T2> <T2, Y, 10, 5> <COMMIT (T2)> <FLUSH LOG> copy value of X, Y to the archive <END CHECKPOINT T2> <END DUMP>