How does mergeout purge data marked for deletion?
A.
It creates delete vectors, identifying files that can be removed from the system.
B.
It updates files by removing records marked with delete vectors.
C.
It writes undeleted records to files in a new location, then deletes all source files.
D.
It writes deleted records to files in a new location, then deletes all source files.
Explanation:
Option A doesn’t look correct.
A mergeout itself doesn’t create delete vectors. They are created by running DELETE. Actual data removal is performed by PURGE command which is executed either by mergeout automatically or can be ran manually.
I think correct answer is C, so it consists of 2 steps. First we consolidate ROS containers, so resulting containers will contain just valid data. Then unused files are deleted physically.
Any thoughts ?
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I do not think that Vertica writes all undeleted data to another location and then delete all source files. Because it is too expensive
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Alexey ,
this question is similar to question 16. What do you think about question 16 ?
Can you check it ?
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Firat, I have added my comment under 16 page, but don’t think it may shed any light on this question – Q26 somehow. In this case It is mostly related how PURGE behaves, I tried to dig vertica docs, but could not find so detailed explanation. Here we have 3 candidates B, C and D, and as I already mentioned above my preference is C.
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