src-d · ajnavarro · Apr 11, 2019 · Apr 10, 2019 · Apr 10, 2019 · Apr 10, 2019
@@ -95,6 +95,36 @@ We support and actively test against certain third-party clients to ensure compa
 - `IFNULL(expr1, expr2)`: If expr1 is not NULL, IFNULL() returns expr1; otherwise it returns expr2.
 - `NULLIF(expr1, expr2)`: Returns NULL if expr1 = expr2 is true, otherwise returns expr1.
 
+## Configuration
+
+The behaviour of certain parts of go-mysql-server can be configured using either environment variables or session variables.
+
+Session variables are set using the following SQL queries:
+
+```sql
+SET <variable name> = <value>
+```
+
+### Memory joins
+
+
+- `INMEMORY_JOINS`: if this environment variable is set it will perform all joins in memory. Default is off.
+- `inmemory_joins`: if this session variable is set it will perform all joins in memory. Default is off. This has precedence over `INMEMORY_JOINS`.
+
+### Maximum inner join memory
+
+- `MAX_MEMORY_INNER_JOIN`: this environment variable controls in megabytes the maximum number of memory that can be consumed by go-mysql-server before switching to multipass mode in inner joins. Default is the 20% of all available physical memory.
+- `max_memory_joins`: this session variable controls in megabytes the maximum number of memory that can be consumed by go-mysql-server before switching to multipass mode in inner joins. Default is the 20% of all available physical memory. This has precedence over `MAX_MEMORY_INNER_JOIN`.
+
+### Debug
+
+- `DEBUG_ANALYZER`: if this environment variable is set, the analyzer will print debug messages. Default is off.
+
+### Index creation threads
+
+- `PILOSA_INDEX_THREADS`: this environment variable sets the number of threads used in index creation. Default is the number of cores available in the machine.
+- `pilosa_index_threads`: this session variable sets the number of threads used in index creation. Default is the number of cores available in the machine. This has precedence over `PILOSA_INDEX_THREADS`.
+
 ## Example
 
 `go-mysql-server` contains a SQL engine and server implementation. So, if you want to start a server, first instantiate the engine and pass your `sql.Database` implementation.

@@ -15,10 +15,10 @@ import (
 )
 
 const (
-	experimentalInMemoryJoinKey = "EXPERIMENTAL_IN_MEMORY_JOIN"
-	maxMemoryJoinKey            = "MAX_MEMORY_INNER_JOIN"
-	inMemoryJoinSessionVar      = "inmemory_joins"
-	memoryThresholdSessionVar   = "max_memory_joins"
+	inMemoryJoinKey           = "INMEMORY_JOINS"
+	maxMemoryJoinKey          = "MAX_MEMORY_INNER_JOIN"
+	inMemoryJoinSessionVar    = "inmemory_joins"
+	memoryThresholdSessionVar = "max_memory_joins"
 )
 
 var (
@@ -32,7 +32,7 @@ var (
 )
 
 func shouldUseMemoryJoinsByEnv() bool {
-	v := strings.TrimSpace(strings.ToLower(os.Getenv(experimentalInMemoryJoinKey)))
+	v := strings.TrimSpace(strings.ToLower(os.Getenv(inMemoryJoinKey)))
 	return v == "on" || v == "1"
 }
 
@@ -48,7 +48,7 @@ func loadMemoryThreshold() uint64 {
 		return defaultMemoryThreshold
 	}
 
-	return n
+	return n * 1024 // to bytes
 }
 
 // InnerJoin is an inner join between two tables.
@@ -252,7 +252,7 @@ func (i *innerJoinIter) fitsInMemory() bool {
 	var maxMemory uint64
 	_, v := i.ctx.Session.Get(memoryThresholdSessionVar)
 	if n, ok := v.(int64); ok {
-		maxMemory = uint64(n)
+		maxMemory = uint64(n) * 1024 // to bytes
 	} else {
 		maxMemory = maxMemoryJoin
 	}