From d51c69789ba70d69dc14c95372a82dc058850a90 Mon Sep 17 00:00:00 2001
From: Andrew Lamb <andrew@nerdnetworks.org>
Date: Thu, 8 Aug 2024 14:35:29 -0400
Subject: [PATCH] Document how to write bloom filters

---
 parquet/src/file/metadata/writer.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/parquet/src/file/metadata/writer.rs b/parquet/src/file/metadata/writer.rs
index 484520252d4b..d7eaebdfbd62 100644
--- a/parquet/src/file/metadata/writer.rs
+++ b/parquet/src/file/metadata/writer.rs
@@ -207,6 +207,11 @@ impl<'a, W: Write> ThriftMetadataWriter<'a, W> {
 /// BloomFilters stored in separate structures whose locations are stored as
 /// offsets from the beginning of the file.
 ///
+/// Note: this writer does not directly write BloomFilters. In order to write
+/// BloomFilters, write the bloom filters into the buffer before creating the
+/// metadata writer. Then set the corresponding `bloom_filter_offset` and
+/// `bloom_filter_length` on [`ColumnChunkMetaData`] passed to this writer.
+///
 /// # Output Format
 ///
 /// The format of the metadata is as follows:
@@ -218,6 +223,7 @@ impl<'a, W: Write> ThriftMetadataWriter<'a, W> {
 /// 5. Parquet Magic Bytes (4 bytes)
 ///
 /// [`FileMetaData`]: crate::format::FileMetaData
+/// [`ColumnChunkMetaData`]: crate::file::metadata::ColumnChunkMetaData
 ///
 /// ```text
 /// ┌──────────────────────┐