parquet plain dict bench

[Rich-T-kid]

Which issue does this PR close?

• works towards optimize PLAIN string columns in parquet to dictionary array #10590
• works towards Epic: Cost-Based Dictionary Encoding datafusion#24111

Rationale for this change

see #10590

What changes are included in this PR?

introduces benchmarks for reading string values into dictionary arrays

Are these changes tested?

n/a

Are there any user-facing changes?

no

[Jefffrey]

something i noticed was the other benches in this file seem to be at the page iterator or array reader level, whilst this new one is pretty much at the top level with the record batch reader api

is this something to be concerned about, or the behaviour we're trying to benchmark here can only be done via the top level api?

[Rich-T-kid]

something i noticed was the other benches in this file seem to be at the page iterator or array reader level, whilst this new one is pretty much at the top level with the record batch reader api

is this something to be concerned about, or the behaviour we're trying to benchmark here can only be done via the top level api?

@Jefffrey The existing benchmarks measure the time to decode an already dictionary-encoded Parquet page into an Arrow dictionary array. This PR's benchmarks measure converting a plain-encoded (non-dictionary) string column into a dictionary array.

I used the top-level API here because it's the less verbose, and mirrors how I'd expect DataFusion to actually use it. That said, it's likely possible to do something similar with the finer-grained APIs. should I update the PR?

[Jefffrey]

should be fine, thanks