Pythian Group

This is the third post in Oracle GoldenGate Extract Internals series (links to part I and part II).

In this post, we’re going to take a closer look at various queries that the Extract process uses against the database. As before, we will start by examining the strace output:

nanosleep({1, 0}, NULL)                 = 0
...
read(20, "\1\"\0\0\255\1\0\0\217\0\0\0H\200\366\256\5\24\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 1024000) = 1024000
...
write(16, "\0$\0\0\6\0\0\0\0\0\3N'\7\0\0\0\2\0\0\0`\0\0\0\0\0\0\0\7\0011"..., 36) = 36
read(17, "\0\351\0\0\6\0\0\0\0\0\6\1\"\375\2\0\0\0\0\0\2\0\0\0\0\0\0\0\0\0\0\0"..., 8208) = 233
write(16, "\0 \0\0\6\0\0\0\0\0\3N(\10\0\0\0\2\0\0\0`\0\0\0\0\0\0\0\7\0011", 32) = 32
read(17, "\0\343\0\0\6\0\0\0\0\0\6\1\"\7\1\0\0\0\0\0\2\0\0\0\0\0\0\0\0\0\0\0"..., 8208) = 227
write(16, "\0K\0\0\6\0\0\0\0\0\3N)\t\0\0\0\2\0\0\0`\0\0\0\0\0\0\0\7,/"..., 75) = 75
read(17, "\0\341\0\0\6\0\0\0\0\0\6\1\"\375\1\0\0\0\0\0\2\0\0\0\0\0\0\0\0\0\0\0"..., 8208) = 225
write(16, "\0Q\0\0\6\0\0\0\0\0\3N*\n\0\0\0\2\0\0\0`\0\0\0\0\0\0\0\7,/"..., 81) = 81
read(17, "\0\254\0\0\6\0\0\0\0\0\4\1\0\0\0)\0\1\0\0\0\0{\5\0\0\0\0\n\0\0\0"..., 8208) = 172
lseek(20, 227328, SEEK_SET)             = 227328
nanosleep({1, 0}, NULL)                 = 0

File descriptors 16 and 17 are the pipes for one of the bequeath connections we have with the database. There are four queries being submitted each cycle (following the same order as those being sent to a database): Read the rest of this entry . . .

Today we continue looking at various aspects of how the Oracle GoldenGate extract process works.

One of the follow up questions to part I was about the way the Extract process reads from ASM storage. I’ve provided the answer, however, today we’re going get a detailed look at how the Extract process interacts with an ASM instance and what kind of implications may result.

Read the rest of this entry . . .