docs: improve functions reference

.github/workflows/linter.yml

@@ -19,3 +19,5 @@ jobs:
         config_file: .markdownlint.yaml
     - name: Check typos
       uses: crate-ci/typos@master
+      with:
+        config: .typo.toml

.typo.toml

@@ -0,0 +1,2 @@
+[files]
+extend-exclude = ["*/**/df-functions.md"]

docs/misc/update_functions.rb

@@ -0,0 +1,80 @@
+#!/usr/bin/ruby
+## A script to update functions in nightly references
+## Usage: ruby misc/update_functions.rb [nightly | v0.x]
+# encoding: utf-8
+require 'net/http'
+
+scalar_functions = {
+  :name => "DataFusion Scalar Functions",
+  :url => "https://raw.githubusercontent.com/apache/datafusion/main/docs/source/user-guide/sql/scalar_functions.md"
+}
+agg_functions = {
+  :name => "DataFusion Aggregate Functions",
+  :url => "https://raw.githubusercontent.com/apache/datafusion/main/docs/source/user-guide/sql/aggregate_functions.md"
+}
+window_functions = {
+  :name => "DataFusion Window Functions",
+  :url => "https://raw.githubusercontent.com/apache/datafusion/main/docs/source/user-guide/sql/window_functions.md"
+}
+
+## Apache DataFusion functions
+datafusion_functions = [scalar_functions, agg_functions, window_functions]
+
+
+def process_headlines(line)
+  ## Add a level of headlines
+  if line =~ /^\s*(#+)\s/
+    replacement = "#{$1}#"
+    ## We don't want to render the function names in right menu bar
+    replacement += "#" if replacement.length >= 4
+    line.gsub! $1, replacement
+  end
+  line
+end
+
+def fix_links(line)
+  ## Fix link: #a_b_c -> #a-b-c
+  line.gsub!(/(#[a-zA-Z0-9_]+)\)/) { |match| match.gsub("_", "-") }
+  ## Fix link: a_b_c.md -> #a-b-c
+  line.gsub!(/\]\(([a-zA-Z0-9_]+\.md)\)/) { |match|
+    match.gsub("_", "-").gsub(".md", "").gsub("](", "](#")
+  }
+
+  line
+end
+
+
+File.open("temp.md", "w") do |f|
+  f.puts("# DataFusion Functions")
+  f.puts("This page is generated from the Apache DataFusion project's documents:")
+
+  for doc in datafusion_functions
+    name = doc[:name]
+    url = doc[:url]
+    markdown = "  * [#{name}](#{url})"
+    f.puts markdown
+  end
+
+  f.puts
+
+  for doc in datafusion_functions
+    uri = URI(doc[:url])
+    markdown = Net::HTTP.get(uri).force_encoding(Encoding::UTF_8)
+
+    lines = markdown.split(/\n/)
+
+    lines.map! do |line|
+      line = process_headlines(line)
+      line = fix_links(line)
+      line
+    end
+
+    f.puts lines.join("\n")
+  end
+end
+
+target = ARGV[0] || "nightly"
+
+File.rename "temp.md", "#{target}/en/reference/sql/df-functions.md"
+
+puts "#{target}/en/reference/sql/df-functions.md updated!"

docs/nightly/en/faq-and-others/faq.md

@@ -145,7 +145,7 @@ Of course, please use the `compact_table` function:
 select compact_table("test");
 ```
 
-There are many [administration functions](/reference/sql/functions#admin-functions) for database management.
+There are many [administration functions](/reference/sql/functions/overview#admin-functions) for database management.
 
 ### Can GreptimeDB be used to store logs?