Fix errors and grammar in BloomFilter.md and PageIndex.md

BloomFilter.md

@@ -122,7 +122,7 @@ boolean block_check(block b, unsigned int32 x) {
   for i in [0..7] {
     for j in [0..31] {
       if (masked.getWord(i).isSet(j)) {
-        if (not b.getWord(i).setBit(j)) {
+        if (not b.getWord(i).isSet(j)) {
           return false
         }
       }
@@ -266,8 +266,8 @@ false positive rates:
 #### File Format
 
 Each multi-block Bloom filter is required to work for only one column chunk. The data of a multi-block
-bloom filter consists of the bloom filter header followed by the bloom filter bitset. The bloom filter
-header encodes the size of the bloom filter bit set in bytes that is used to read the bitset.
+Bloom filter consists of the Bloom filter header followed by the Bloom filter bitset. The Bloom filter
+header encodes the size of the Bloom filter bitset in bytes that is used to read the bitset.
 
 Here are the Bloom filter definitions in thrift:
 
@@ -282,7 +282,7 @@ union BloomFilterAlgorithm {
 }
 
 /** Hash strategy type annotation. xxHash is an extremely fast non-cryptographic hash
- * algorithm. It uses 64 bits version of xxHash. 
+ * algorithm. It uses the 64-bit version of xxHash.
  **/
 struct XxHash {}
 
@@ -307,21 +307,29 @@ union BloomFilterCompression {
   * Bloom filter header is stored at beginning of Bloom filter data of each column
   * and followed by its bitset.
   **/
-struct BloomFilterPageHeader {
-  /** The size of bitset in bytes **/
+struct BloomFilterHeader {
+  /** The size of bitset in bytes. **/
   1: required i32 numBytes;
   /** The algorithm for setting bits. **/
   2: required BloomFilterAlgorithm algorithm;
   /** The hash function used for Bloom filter. **/
   3: required BloomFilterHash hash;
-  /** The compression used in the Bloom filter **/
+  /** The compression used in the Bloom filter. **/
   4: required BloomFilterCompression compression;
 }
 
 struct ColumnMetaData {
   ...
   /** Byte offset from beginning of file to Bloom filter data. **/
   14: optional i64 bloom_filter_offset;
+
+  /** Size of Bloom filter data including the serialized header, in bytes.
+   * Added in 2.10 so readers may not read this field from old files and
+   * it can be obtained after the BloomFilterHeader has been deserialized.
+   * Writers should write this field so readers can read the bloom filter
+   * in a single I/O.
+   */
+  15: optional i32 bloom_filter_length;
 }
 
 ```
@@ -339,8 +347,8 @@ information such as the presence of value. Therefore the Bloom filter of columns
 data should be encrypted with the column key, and the Bloom filter of other (not sensitive) columns
 do not need to be encrypted.
 
-Bloom filters have two serializable modules - the PageHeader thrift structure (with its internal
-fields, including the BloomFilterPageHeader `bloom_filter_page_header`), and the Bitset. The header
+Bloom filters have two serializable modules - the Bloom filter header (the BloomFilterHeader thrift
+structure and its internal fields), and the Bitset. The header
 structure is serialized by Thrift, and written to file output stream; it is followed by the
 serialized Bitset.
 

PageIndex.md

@@ -17,13 +17,13 @@
   - under the License.
   -->
 
-# Parquet page index: Layout to Support Page Skipping
+# Parquet Page Index: Layout to Support Page Skipping
 
 In Parquet, a *page index* is optional metadata for a
 ColumnChunk, containing statistics for DataPages that can be used
 to skip those pages when scanning in ordered and unordered columns.
 The page index is stored using the OffsetIndex and ColumnIndex structures,
-defined in [`parquet.thrift`](src/main/thrift/parquet.thrift)
+defined in [`parquet.thrift`](src/main/thrift/parquet.thrift).
 
 ## Problem Statement
 In previous versions of the format, Statistics are stored for ColumnChunks in
@@ -37,7 +37,7 @@ data from disk.
 1. Make both range scans and point lookups I/O efficient by allowing direct
    access to pages based on their min and max values. In particular:
     *  A single-row lookup in a row group based on the sort column of that row group
-  will only read one data page per the retrieved column.
+  will only read one data page per retrieved column.
     * Range scans on the sort column will only need to read the exact data 
       pages that contain relevant data.
     * Make other selective scans I/O efficient: if we have a very selective
@@ -81,7 +81,7 @@ Some observations:
 * We store lower and upper bounds for the values of each page. These may be the
   actual minimum and maximum values found on a page, but can also be (more
   compact) values that do not exist on a page. For example, instead of storing
-  ""Blart Versenwald III", a writer may set `min_values[i]="B"`,
+  `"Blart Versenwald III"`, a writer may set `min_values[i]="B"`,
   `max_values[i]="C"`. This allows writers to truncate large values and writers
   should use this to enforce some reasonable bound on the size of the index
   structures.