zhuqi-lucas commented on code in PR #186:
URL: https://github.com/apache/datafusion-site/pull/186#discussion_r3544641569
##########
content/blog/2026-07-05-sort-pushdown.md:
##########
@@ -0,0 +1,625 @@
+---
+layout: post
+title: Sort Pushdown in DataFusion: Skip Sorts, Skip Decode, Skip I/O
+date: 2026-07-05
+author: Qi Zhu
+categories: [performance]
+---
+
+<!--
+{% comment %}
+Licensed to the Apache Software Foundation (ASF) under one or more
+contributor license agreements. See the NOTICE file distributed with
+this work for additional information regarding copyright ownership.
+The ASF licenses this file to you under the Apache License, Version 2.0
+(the "License"); you may not use this file except in compliance with
+the License. You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+{% endcomment %}
+-->
+
+[TOC]
+
+*Qi Zhu, [Massive](https://www.massive.com/)*
+
+**[Apache DataFusion] now automatically takes advantage of sortedness in the
Review Comment:
Done — dropped `now`.
##########
content/blog/2026-07-05-sort-pushdown.md:
##########
@@ -0,0 +1,625 @@
+---
+layout: post
+title: Sort Pushdown in DataFusion: Skip Sorts, Skip Decode, Skip I/O
+date: 2026-07-05
+author: Qi Zhu
+categories: [performance]
+---
+
+<!--
+{% comment %}
+Licensed to the Apache Software Foundation (ASF) under one or more
+contributor license agreements. See the NOTICE file distributed with
+this work for additional information regarding copyright ownership.
+The ASF licenses this file to you under the Apache License, Version 2.0
+(the "License"); you may not use this file except in compliance with
+the License. You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+{% endcomment %}
+-->
+
+[TOC]
+
+*Qi Zhu, [Massive](https://www.massive.com/)*
+
+**[Apache DataFusion] now automatically takes advantage of sortedness in the
+data — even when the data is only *partially* sorted, and even when
+DataFusion has not been told about the ordering ahead of time.** This post
+explains why that matters and walks through how DataFusion achieves it,
+through a combination of plan-time sort pushdown, runtime scan reordering,
+and mid-scan row-group pruning driven by [dynamic filters][dyn-filters-blog].
+
+[Apache DataFusion]: https://datafusion.apache.org/
+[dyn-filters-blog]:
https://datafusion.apache.org/blog/2025/09/10/dynamic-filters/
+
+## Why sort pushdown matters
+
+Many real datasets are at least partly sorted on disk:
Review Comment:
Done — `sorted on disk` → `sorted when stored`.
##########
content/blog/2026-07-05-sort-pushdown.md:
##########
@@ -0,0 +1,625 @@
+---
+layout: post
+title: Sort Pushdown in DataFusion: Skip Sorts, Skip Decode, Skip I/O
+date: 2026-07-05
+author: Qi Zhu
+categories: [performance]
+---
+
+<!--
+{% comment %}
+Licensed to the Apache Software Foundation (ASF) under one or more
+contributor license agreements. See the NOTICE file distributed with
+this work for additional information regarding copyright ownership.
+The ASF licenses this file to you under the Apache License, Version 2.0
+(the "License"); you may not use this file except in compliance with
+the License. You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+{% endcomment %}
+-->
+
+[TOC]
+
+*Qi Zhu, [Massive](https://www.massive.com/)*
+
+**[Apache DataFusion] now automatically takes advantage of sortedness in the
+data — even when the data is only *partially* sorted, and even when
+DataFusion has not been told about the ordering ahead of time.** This post
+explains why that matters and walks through how DataFusion achieves it,
+through a combination of plan-time sort pushdown, runtime scan reordering,
+and mid-scan row-group pruning driven by [dynamic filters][dyn-filters-blog].
+
+[Apache DataFusion]: https://datafusion.apache.org/
+[dyn-filters-blog]:
https://datafusion.apache.org/blog/2025/09/10/dynamic-filters/
+
+## Why sort pushdown matters
+
+Many real datasets are at least partly sorted on disk:
+
+- Time-series files are written in ingestion-time order.
+- Event logs are sharded and sorted by event id.
+- Partitioned tables have a natural ordering by partition key.
+- Modern data lakes based on [Apache Iceberg] and similar formats
+ often have to work with data **as it was written** — resorting the
+ whole table isn't an option.
Review Comment:
Done — adopted suggested Iceberg bullet.
##########
content/blog/2026-07-05-sort-pushdown.md:
##########
@@ -0,0 +1,625 @@
+---
+layout: post
+title: Sort Pushdown in DataFusion: Skip Sorts, Skip Decode, Skip I/O
+date: 2026-07-05
+author: Qi Zhu
+categories: [performance]
+---
+
+<!--
+{% comment %}
+Licensed to the Apache Software Foundation (ASF) under one or more
+contributor license agreements. See the NOTICE file distributed with
+this work for additional information regarding copyright ownership.
+The ASF licenses this file to you under the Apache License, Version 2.0
+(the "License"); you may not use this file except in compliance with
+the License. You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+{% endcomment %}
+-->
+
+[TOC]
+
+*Qi Zhu, [Massive](https://www.massive.com/)*
+
+**[Apache DataFusion] now automatically takes advantage of sortedness in the
+data — even when the data is only *partially* sorted, and even when
+DataFusion has not been told about the ordering ahead of time.** This post
+explains why that matters and walks through how DataFusion achieves it,
+through a combination of plan-time sort pushdown, runtime scan reordering,
+and mid-scan row-group pruning driven by [dynamic filters][dyn-filters-blog].
+
+[Apache DataFusion]: https://datafusion.apache.org/
+[dyn-filters-blog]:
https://datafusion.apache.org/blog/2025/09/10/dynamic-filters/
+
+## Why sort pushdown matters
+
+Many real datasets are at least partly sorted on disk:
+
+- Time-series files are written in ingestion-time order.
+- Event logs are sharded and sorted by event id.
+- Partitioned tables have a natural ordering by partition key.
+- Modern data lakes based on [Apache Iceberg] and similar formats
+ often have to work with data **as it was written** — resorting the
+ whole table isn't an option.
+
+But that "pre-existing sortedness" is only useful if the query engine can
+**notice** it and **use** it. Two common failure modes:
+
+1. The engine doesn't know about the ordering — the writer didn't set
+ Parquet `sorting_columns`, and the table definition doesn't include a
Review Comment:
Done — linked Parquet `sorting_columns` to thrift; clarified `WITH ORDER` as
DataFusion-specific.
##########
content/blog/2026-07-05-sort-pushdown.md:
##########
@@ -0,0 +1,625 @@
+---
+layout: post
+title: Sort Pushdown in DataFusion: Skip Sorts, Skip Decode, Skip I/O
+date: 2026-07-05
+author: Qi Zhu
+categories: [performance]
+---
+
+<!--
+{% comment %}
+Licensed to the Apache Software Foundation (ASF) under one or more
+contributor license agreements. See the NOTICE file distributed with
+this work for additional information regarding copyright ownership.
+The ASF licenses this file to you under the Apache License, Version 2.0
+(the "License"); you may not use this file except in compliance with
+the License. You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+{% endcomment %}
+-->
+
+[TOC]
+
+*Qi Zhu, [Massive](https://www.massive.com/)*
+
+**[Apache DataFusion] now automatically takes advantage of sortedness in the
+data — even when the data is only *partially* sorted, and even when
+DataFusion has not been told about the ordering ahead of time.** This post
+explains why that matters and walks through how DataFusion achieves it,
+through a combination of plan-time sort pushdown, runtime scan reordering,
+and mid-scan row-group pruning driven by [dynamic filters][dyn-filters-blog].
+
+[Apache DataFusion]: https://datafusion.apache.org/
+[dyn-filters-blog]:
https://datafusion.apache.org/blog/2025/09/10/dynamic-filters/
+
+## Why sort pushdown matters
+
+Many real datasets are at least partly sorted on disk:
+
+- Time-series files are written in ingestion-time order.
+- Event logs are sharded and sorted by event id.
+- Partitioned tables have a natural ordering by partition key.
+- Modern data lakes based on [Apache Iceberg] and similar formats
+ often have to work with data **as it was written** — resorting the
+ whole table isn't an option.
+
+But that "pre-existing sortedness" is only useful if the query engine can
+**notice** it and **use** it. Two common failure modes:
+
+1. The engine doesn't know about the ordering — the writer didn't set
+ Parquet `sorting_columns`, and the table definition doesn't include a
+ [`WITH
ORDER`](https://datafusion.apache.org/user-guide/sql/ddl.html#create-external-table)
clause.
+2. The engine knows the *per-file* ordering, but the file *listing* on
+ disk is in a different order, so global sortedness can't be proven at
+ plan time.
+
+In both cases, an `ORDER BY` or `ORDER BY ... LIMIT N` query pays the
+cost of a full external `SortExec` — a pipeline-blocking operator that
+must see every input row before emitting anything, dominating both
+latency and peak memory on large scans.
Review Comment:
Done — `full external SortExec` → `full sort`; `see` → `buffer`.
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