keith-turner opened a new issue #1974:
URL: https://github.com/apache/accumulo/issues/1974
**Is your feature request related to a problem? Please describe.**
While working on #1451 I ran into a situation where I needed to read
metadata for multiple non-contiguous tablets from the metadata table. To do
this using Ample currently requires an RPC for each tablet, which is
inefficient. Ample currently only supports reading a range of contiguous
tablets or a single tablet.
**Describe the solution you'd like**
Given a collection of KeyExtents I would like to be able to lookup the
related tablet metadata with code like the following.
```java
ServerContext context = ....;
Collection<KeyExtent> extents= ...;
Iterable<TabletMetadata> tabletsMeta = context.getAmple().
readTablets().
forTablets(extents). // this would be
a new method
fetch(ColumnType.LOCATION,
ColumnType.PREV_ROW).
build();
for (TabletMetadata tabletMetadata : tabletsMeta) {
// use metadata
}
```
The implementation within Ample for this new method could use a BatchScanner
and WholeRowIterator
**Describe alternatives you've considered**
I could use a BatchScanner and WholeIterator directly within the code I am
writing, however that would be less maintainable. Until this implemented I
will do the following which is less efficient (RPC per extent) but maintainable
and easy to understand.
```java
ServerContext context = ....;
Collection<KeyExtent> extents= ...;
for (KeyExtent extent : extents) {
TabletMetadata tabletMetadata = context.getAmple().readTablet(extent,
ColumnType.LOCATION, ColumnType.PREV_ROW);
// use metadata
}
```
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