From dc6e34075e690e27c718ce2b504b2abc10308f0e Mon Sep 17 00:00:00 2001
From: Michael Kolupaev <michael.kolupaev@clickhouse.com>
Date: Mon, 13 Mar 2023 18:51:56 +0000
Subject: [PATCH] Read less unnecessary data from Parquet files

---
 src/Core/Settings.h                    |  2 +-
 src/IO/ReadBufferFromS3.cpp            | 20 +++++++++++++++++++-
 src/IO/ReadBufferFromS3.h              |  1 +
 src/Processors/Formats/ISchemaReader.h |  2 +-
 4 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/src/Core/Settings.h b/src/Core/Settings.h
index c47432ae14a..5e4124462a3 100644
--- a/src/Core/Settings.h
+++ b/src/Core/Settings.h
@@ -638,7 +638,7 @@ class IColumn;
     M(Int64, read_priority, 0, "Priority to read data from local filesystem. Only supported for 'pread_threadpool' method.", 0) \
     M(UInt64, merge_tree_min_rows_for_concurrent_read_for_remote_filesystem, (20 * 8192), "If at least as many lines are read from one file, the reading can be parallelized, when reading from remote filesystem.", 0) \
     M(UInt64, merge_tree_min_bytes_for_concurrent_read_for_remote_filesystem, (24 * 10 * 1024 * 1024), "If at least as many bytes are read from one file, the reading can be parallelized, when reading from remote filesystem.", 0) \
-    M(UInt64, remote_read_min_bytes_for_seek, 4 * DBMS_DEFAULT_BUFFER_SIZE, "Min bytes required for remote read (url, s3) to do seek, instead for read with ignore.", 0) \
+    M(UInt64, remote_read_min_bytes_for_seek, 4 * DBMS_DEFAULT_BUFFER_SIZE, "Min bytes required for remote read (url, s3) to do seek, instead of read with ignore.", 0) \
     \
     M(UInt64, async_insert_threads, 16, "Maximum number of threads to actually parse and insert data in background. Zero means asynchronous mode is disabled", 0) \
     M(Bool, async_insert, false, "If true, data from INSERT query is stored in queue and later flushed to table in background. Makes sense only for inserts via HTTP protocol. If wait_for_async_insert is false, INSERT query is processed almost instantly, otherwise client will wait until data will be flushed to table", 0) \
diff --git a/src/IO/ReadBufferFromS3.cpp b/src/IO/ReadBufferFromS3.cpp
index 91905330b74..bf95bf59151 100644
--- a/src/IO/ReadBufferFromS3.cpp
+++ b/src/IO/ReadBufferFromS3.cpp
@@ -270,7 +270,25 @@ void ReadBufferFromS3::setReadUntilPosition(size_t position)
     if (position != static_cast<size_t>(read_until_position))
     {
         read_until_position = position;
-        impl.reset();
+        if (impl)
+        {
+            // Not exactly a seek, but close enough.
+            ProfileEvents::increment(ProfileEvents::ReadBufferSeekCancelConnection);
+            impl.reset();
+        }
+    }
+}
+
+void ReadBufferFromS3::setReadUntilEnd()
+{
+    if (read_until_position)
+    {
+        read_until_position = 0;
+        if (impl)
+        {
+            ProfileEvents::increment(ProfileEvents::ReadBufferSeekCancelConnection);
+            impl.reset();
+        }
     }
 }
 
diff --git a/src/IO/ReadBufferFromS3.h b/src/IO/ReadBufferFromS3.h
index 84e8d36865c..ad0430d35b1 100644
--- a/src/IO/ReadBufferFromS3.h
+++ b/src/IO/ReadBufferFromS3.h
@@ -69,6 +69,7 @@ public:
     size_t getFileSize() override;
 
     void setReadUntilPosition(size_t position) override;
+    void setReadUntilEnd() override;
 
     Range getRemainingReadRange() const override;
 
diff --git a/src/Processors/Formats/ISchemaReader.h b/src/Processors/Formats/ISchemaReader.h
index e6982ea743b..78b34a07840 100644
--- a/src/Processors/Formats/ISchemaReader.h
+++ b/src/Processors/Formats/ISchemaReader.h
@@ -16,7 +16,7 @@ namespace ErrorCodes
 }
 
 /// Base class for schema inference for the data in some specific format.
-/// It reads some data from read buffer and try to determine the schema
+/// It reads some data from read buffer and tries to determine the schema
 /// from read data.
 class ISchemaReader
 {