renamed variables and struct fields #746

Job	Run time
cargo check	9m 9s
build with wasm-pack	2m 24s
cargo test (macos)	19m 31s
cargo test (win64)	44m 18s
Check cargo fmt	35s
cargo test (macos-aarch64)	9m 43s
Verify MSRV (Min Supported Rust Version)	7m 13s
Verify Vendored Code	47s
verify benchmark results (amd64)	10m 22s
cargo test doc (amd64)	12m 11s
cargo examples (amd64)	10m 57s
cargo doc	3m 44s
circular dependency check	2m 29s
Run sqllogictest with Postgres runner	3m 0s
check Cargo.toml formatting	3m 1s
clippy	5m 6s
check configs.md is up-to-date	2m 39s
cargo test hash collisions (amd64)	9m 49s
cargo test (amd64)	10m 37s
cargo test datafusion-cli (amd64)	3m 34s
cargo test pyarrow (amd64)	2m 50s
	2h 53m 59s

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