[GitHub] [accumulo] dlmarion edited a comment on pull request #2422: Implementation of Scan Servers.

[GitBox <gi...@apache.org>]

dlmarion edited a comment on pull request #2422:
URL: https://github.com/apache/accumulo/pull/2422#issuecomment-1024522042


   Some annotated shell output:
   ```bash
   root@test> createtable test (1)
   root@test test> insert a b c d (2)
   root@test test> scan (3)
   a b:c []	d
   root@test test> scan -cl immediate (4)
   a b:c []	d
   root@test test> scan -cl eventual (5)
   root@test test> flush (6)
   2022-01-28T18:58:10,693 [shell.Shell] INFO : Flush of table test  initiated...
   root@test test> scan (7)
   a b:c []	d
   root@test test> scan -cl eventual (8)
   a b:c []	d
   ```
   
   I create a table (1) and insert some date (2). When I run a scan (3,4) with the `immediate` consistency level, which happens to be the default, the scan uses normal code path and issues the scan command against the tablet server. Data is returned because the tablet server code path also returns data that is in the in-memory map. When I scan with the `eventual` consistency level no data is returned because the code path in the scanner only uses the data in the tablet's files. When I flush (6) the data to write a file in HDFS, the subsequent scans with `immediate` (7) and `eventual` (8) consistency level return the data.


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