From f1b98ed7cfcc16047750d5c81eae4344123a9eac Mon Sep 17 00:00:00 2001
From: David Taylor <tinystatemachine@gmail.com>
Date: Tue, 23 Jan 2024 20:16:27 +0000
Subject: [PATCH] sstable: capture elided prefix in a prop

---
 sstable/properties.go   | 7 ++++++-
 sstable/testdata/writer | 4 +++-
 sstable/writer.go       | 1 +
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/sstable/properties.go b/sstable/properties.go
index 3bbf34a8afc..53932d73d2e 100644
--- a/sstable/properties.go
+++ b/sstable/properties.go
@@ -134,6 +134,9 @@ type Properties struct {
 	CompressionOptions string `prop:"rocksdb.compression_options"`
 	// The total size of all data blocks.
 	DataSize uint64 `prop:"rocksdb.data.size"`
+	// ElidedPrefix is the byte prefix, if any, that was elided from every key and
+	// key span during the construction of the sstable.
+	ElidedPrefix string `prop:"pebble.elided_prefix"`
 	// The external sstable version format. Version 2 is the one RocksDB has been
 	// using since 5.13. RocksDB only uses the global sequence number for an
 	// sstable if this property has been set.
@@ -428,7 +431,9 @@ func (p *Properties) save(tblFormat TableFormat, w *rawBlockWriter) {
 		p.saveUvarint(m, unsafe.Offsetof(p.ValueBlocksSize), p.ValueBlocksSize)
 	}
 	p.saveBool(m, unsafe.Offsetof(p.WholeKeyFiltering), p.WholeKeyFiltering)
-
+	if p.ElidedPrefix != "" {
+		p.saveString(m, unsafe.Offsetof(p.ElidedPrefix), p.ElidedPrefix)
+	}
 	if tblFormat < TableFormatPebblev1 {
 		m["rocksdb.column.family.id"] = binary.AppendUvarint([]byte(nil), math.MaxInt32)
 		m["rocksdb.fixed.key.length"] = []byte{0x00}
diff --git a/sstable/testdata/writer b/sstable/testdata/writer
index 44236a09cba..492f9a9dc45 100644
--- a/sstable/testdata/writer
+++ b/sstable/testdata/writer
@@ -369,7 +369,7 @@ layout
        821  footer (53)
        874  EOF
 
-build elide-prefix=foo_
+build elide-prefix=foo_ props=(elided)
 foo_a.SET.1:a
 foo_b.DEL.2:
 foo_c.MERGE.3:c
@@ -386,3 +386,5 @@ point:    [a#1,1-h#7,2]
 rangedel: [d#4,15-j#72057594037927935,15]
 rangekey: [j#9,19-m#72057594037927935,21]
 seqnums:  [1-11]
+props "elided":
+  pebble.elided_prefix: foo_
diff --git a/sstable/writer.go b/sstable/writer.go
index 4322b062c26..08d61365f2d 100644
--- a/sstable/writer.go
+++ b/sstable/writer.go
@@ -2303,6 +2303,7 @@ func NewWriter(writable objstorage.Writable, o WriterOptions, extraOpts ...Write
 	w.props.MergerName = o.MergerName
 	w.props.PropertyCollectorNames = "[]"
 	w.props.ExternalFormatVersion = rocksDBExternalFormatVersion
+	w.props.ElidedPrefix = string(o.ElidePrefix)
 
 	if len(o.BlockPropertyCollectors) > 0 || w.tableFormat >= TableFormatPebblev4 {
 		var buf bytes.Buffer