1 files changed, 63 insertions, 0 deletions
diff --git a/src/include/storage/read_stream.h b/src/include/storage/read_stream.h
new file mode 100644
index 00000000000..fae09d2b4cc
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+++ b/src/include/storage/read_stream.h
@@ -0,0 +1,63 @@
+/*-------------------------------------------------------------------------
+ *
+ * read_stream.h
+ *	  Mechanism for accessing buffered relation data with look-ahead
+ *
+ *
+ * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/storage/read_stream.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef READ_STREAM_H
+#define READ_STREAM_H
+
+#include "storage/bufmgr.h"
+
+/* Default tuning, reasonable for many users. */
+#define READ_STREAM_DEFAULT 0x00
+
+/*
+ * I/O streams that are performing maintenance work on behalf of potentially
+ * many users, and thus should be governed by maintenance_io_concurrency
+ * instead of effective_io_concurrency.  For example, VACUUM or CREATE INDEX.
+ */
+#define READ_STREAM_MAINTENANCE 0x01
+
+/*
+ * We usually avoid issuing prefetch advice automatically when sequential
+ * access is detected, but this flag explicitly disables it, for cases that
+ * might not be correctly detected.  Explicit advice is known to perform worse
+ * than letting the kernel (at least Linux) detect sequential access.
+ */
+#define READ_STREAM_SEQUENTIAL 0x02
+
+/*
+ * We usually ramp up from smaller reads to larger ones, to support users who
+ * don't know if it's worth reading lots of buffers yet.  This flag disables
+ * that, declaring ahead of time that we'll be reading all available buffers.
+ */
+#define READ_STREAM_FULL 0x04
+
+struct ReadStream;
+typedef struct ReadStream ReadStream;
+
+/* Callback that returns the next block number to read. */
+typedef BlockNumber (*ReadStreamBlockNumberCB) (ReadStream *stream,
+												void *callback_private_data,
+												void *per_buffer_data);
+
+extern ReadStream *read_stream_begin_relation(int flags,
+											  BufferAccessStrategy strategy,
+											  Relation rel,
+											  ForkNumber forknum,
+											  ReadStreamBlockNumberCB callback,
+											  void *callback_private_data,
+											  size_t per_buffer_data_size);
+extern Buffer read_stream_next_buffer(ReadStream *stream, void **per_buffer_private);
+extern void read_stream_reset(ReadStream *stream);
+extern void read_stream_end(ReadStream *stream);
+
+#endif							/* READ_STREAM_H */