Remove indexmap dependency #1882
Description
Is your feature request related to a problem or challenge? Please describe what you are trying to do.
We are using the indexmap for a relatively small usecase in the json reader to preserve insertion order.
This version isn't keeping up with dependencies (ses discussion on #1861 (comment))
Describe the solution you'd like
I would like to remove the use of indexmap entirely and streamline the arrow dependency chain
Fascinatingly when I apply the following diff all the tests pass (though I don't think it is entirely correct as BTreeSet and BTreeMap do not actually preserve the insert order) so there is clearly a gap in test coverage too
diff --git a/arrow/Cargo.toml b/arrow/Cargo.toml
index b59a697538..e0008abde4 100644
--- a/arrow/Cargo.toml
+++ b/arrow/Cargo.toml
@@ -41,7 +41,6 @@ bench = false
serde = { version = "1.0", default-features = false }
serde_derive = { version = "1.0", default-features = false }
serde_json = { version = "1.0", default-features = false, features = ["preserve_order"] }
-indexmap = { version = "1.6", default-features = false, features = ["std"] }
rand = { version = "0.8", default-features = false, features = ["std", "std_rng"], optional = true }
num = { version = "0.4", default-features = false, features = ["std"] }
half = { version = "1.8", default-features = false }
diff --git a/arrow/src/json/reader.rs b/arrow/src/json/reader.rs
index e1fa54f8a6..f7384c7e5b 100644
--- a/arrow/src/json/reader.rs
+++ b/arrow/src/json/reader.rs
@@ -50,8 +50,8 @@
use std::io::{BufRead, BufReader, Read, Seek, SeekFrom};
use std::sync::Arc;
-use indexmap::map::IndexMap as HashMap;
-use indexmap::set::IndexSet as HashSet;
+use std::collections::BTreeMap as HashMap;
+use std::collections::BTreeSet as HashSet;
use serde_json::json;
use serde_json::{map::Map as JsonMap, Value};
Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.
Additional context
This code and dependency appears to have come in originally via 8ef1fb8 / apache/arrow#3702 from(@nevi-me)