keith-turner commented on PR #4596:
URL: https://github.com/apache/accumulo/pull/4596#issuecomment-2127507816
> I'm open to suggestions on how to best proceed with this change.
We could attemot the following :
* Create a new prefix for the new data format, maybe `~scanr`
* In 2.1.3 servers would start writing the new format under the new prefix
* Push all of the logic for encoding/decoding to/from key/value into
ScanServerRefTabletFile
* Make ScanServerRefTabletFile internally track the prefix it was decoded
from and it can use that to create mutations
* When scanning to gather ScanServerRefTabletFile, scan both prefixes
Pushing all of the encode/decode into ScanServerRefTabletFile seens like a
nice general improvement on its own because it would bring that logic all to a
single place in the code. Might look something like the following. Then
except for having to scan both prefixes, most of the code dealing w/
ScanServerRefTabletFile would hopefully be oblivious to how the data is
represented.
```java
public class ScanServerRefTabletFile extends TabletFile {
private String prefix; // either old prefix of ~sserv or new one of ~scanr
private Text uuid;
private Text serverAddress;
public ScanServerRefTabletFile(String file, String serverAddress, UUID
serverLockUUID) {
super(new Path(URI.create(file)));
// for new data always use the new prefix
prefix = "~scanr";
uuid = new Text(serverLockUUID.toString());
this.serverAddress = new Text(serverAddress);
}
private boolean isOldPrefix(Key k){
return k.getRow().toString().startsWith("~sserv");
}
private static String extractFile(Key k) {
// TODO extract file from key depending on prefix
}
// create a scan server ref from a mutatiopn
public ScanServerRefTabletFile(Key k, Value v) {
super(new Path(URI.create(extractFile(k))));
// TODO use prefix to determine how to extract uuid and serverAddress
from key/value
}
public void put(Mutation m) {
// TODO use prefix determine how to put uuid, server, and file into the
mutation
}
public void putDelete(Mutation m) {
// TODO use prefix determine how to put delete for uuid, server, and
file into the mutation
}
}
```
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