Convert more documentation to markdown source

* top-level docs
* appendix
* overview
* developer guide

docs/src/main/sphinx/admin.md

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+# Administration
+
+```{toctree}
+:maxdepth: 1
+
+admin/web-interface
+admin/tuning
+admin/jmx
+admin/properties
+admin/spill
+admin/resource-groups
+admin/session-property-managers
+admin/dist-sort
+admin/dynamic-filtering
+admin/graceful-shutdown
+admin/fault-tolerant-execution
+```
+
+# Event listeners
+
+```{toctree}
+:titlesonly: true
+
+admin/event-listeners-http
+```

docs/src/main/sphinx/appendix.md

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+# Appendix
+
+```{toctree}
+:maxdepth: 1
+
+appendix/from-hive
+appendix/legal-notices
+```

docs/src/main/sphinx/appendix/from-hive.md

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+# Migrating from Hive
+
+Trino uses ANSI SQL syntax and semantics, whereas Hive uses a language similar
+to SQL called HiveQL which is loosely modeled after MySQL (which itself has many
+differences from ANSI SQL).
+
+## Use subscript for accessing a dynamic index of an array instead of a udf
+
+The subscript operator in SQL supports full expressions, unlike Hive (which only supports constants). Therefore you can write queries like:
+
+```
+SELECT my_array[CARDINALITY(my_array)] as last_element
+FROM ...
+```
+
+## Avoid out of bounds access of arrays
+
+Accessing out of bounds elements of an array will result in an exception. You can avoid this with an `if` as follows:
+
+```
+SELECT IF(CARDINALITY(my_array) >= 3, my_array[3], NULL)
+FROM ...
+```
+
+## Use ANSI SQL syntax for arrays
+
+Arrays are indexed starting from 1, not from 0:
+
+```
+SELECT my_array[1] AS first_element
+FROM ...
+```
+
+Construct arrays with ANSI syntax:
+
+```
+SELECT ARRAY[1, 2, 3] AS my_array
+```
+
+## Use ANSI SQL syntax for identifiers and strings
+
+Strings are delimited with single quotes and identifiers are quoted with double quotes, not backquotes:
+
+```
+SELECT name AS "User Name"
+FROM "7day_active"
+WHERE name = 'foo'
+```
+
+## Quote identifiers that start with numbers
+
+Identifiers that start with numbers are not legal in ANSI SQL and must be quoted using double quotes:
+
+```
+SELECT *
+FROM "7day_active"
+```
+
+## Use the standard string concatenation operator
+
+Use the ANSI SQL string concatenation operator:
+
+```
+SELECT a || b || c
+FROM ...
+```
+
+## Use standard types for CAST targets
+
+The following standard types are supported for `CAST` targets:
+
+```
+SELECT
+  CAST(x AS varchar)
+, CAST(x AS bigint)
+, CAST(x AS double)
+, CAST(x AS boolean)
+FROM ...
+```
+
+In particular, use `VARCHAR` instead of `STRING`.
+
+## Use CAST when dividing integers
+
+Trino follows the standard behavior of performing integer division when dividing two integers. For example, dividing `7` by `2` will result in `3`, not `3.5`.
+To perform floating point division on two integers, cast one of them to a double:
+
+```
+SELECT CAST(5 AS DOUBLE) / 2
+```
+
+## Use WITH for complex expressions or queries
+
+When you want to re-use a complex output expression as a filter, use either an inline subquery or factor it out using the `WITH` clause:
+
+```
+WITH a AS (
+  SELECT substr(name, 1, 3) x
+  FROM ...
+)
+SELECT *
+FROM a
+WHERE x = 'foo'
+```
+
+## Use UNNEST to expand arrays and maps
+
+Trino supports {ref}`unnest` for expanding arrays and maps.
+Use `UNNEST` instead of `LATERAL VIEW explode()`.
+
+Hive query:
+
+```
+SELECT student, score
+FROM tests
+LATERAL VIEW explode(scores) t AS score;
+```
+
+Trino query:
+
+```
+SELECT student, score
+FROM tests
+CROSS JOIN UNNEST(scores) AS t (score);
+```
+
+## Use ANSI SQL syntax for date and time INTERVAL expressions
+
+Trino supports the ANSI SQL style `INTERVAL` expressions that differs from the implementation used in Hive.
+
+- The `INTERVAL` keyword is required and is not optional.
+- Date and time units must be singular. For example `day` and not `days`.
+- Values must be quoted.
+
+Hive query:
+
+```
+SELECT cast('2000-08-19' as date) + 14 days;
+```
+
+Equivalent Trino query:
+
+```
+SELECT cast('2000-08-19' as date) + INTERVAL '14' day;
+```
+
+## Caution with datediff
+
+The Hive `datediff` function returns the difference between the two dates in
+days and is declared as:
+
+```text
+datediff(string enddate, string startdate)  -> integer
+```
+
+The equivalent Trino function {ref}`date_diff<datetime-interval-functions>`
+uses a reverse order for the two date parameters and requires a unit. This has
+to be taken into account when migrating:
+
+Hive query:
+
+```
+datediff(enddate, startdate)
+```
+
+Trino query:
+
+```
+date_diff('day', startdate, enddate)
+```
+
+## Overwriting data on insert
+
+By default, `INSERT` queries are not allowed to overwrite existing data. You
+can use the catalog session property `insert_existing_partitions_behavior` to
+allow overwrites. Prepend the name of the catalog using the Hive connector, for
+example `hdfs`, and set the property in the session before you run the insert
+query:
+
+```
+SET SESSION hdfs.insert_existing_partitions_behavior = 'OVERWRITE';
+INSERT INTO hdfs.schema.table ...
+```
+
+The resulting behavior is equivalent to using [INSERT OVERWRITE](https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DML) in Hive.
+
+Insert overwrite operation is not supported by Trino when the table is stored on
+encrypted HDFS, when the table is unpartitioned or table is transactional.