Merge pull request #669 from erizocosmico/docs/env-vars

ajnavarro · web-flow · commit 3e54829e8c9c · 2019-04-11T10:22:27.000+02:00
docs: add session and environment variables to README
diff --git a/README.md b/README.md
@@ -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.
diff --git a/sql/plan/innerjoin.go b/sql/plan/innerjoin.go
@@ -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
 	}

Original file line number	Diff line number	Diff line change
`@@ -15,10 +15,10 @@ import (`
`15`	`15`	`)`
`16`	`16`
`17`	`17`	`const (`
`18`		`- experimentalInMemoryJoinKey = "EXPERIMENTAL_IN_MEMORY_JOIN"`
`19`		`- maxMemoryJoinKey = "MAX_MEMORY_INNER_JOIN"`
`20`		`- inMemoryJoinSessionVar = "inmemory_joins"`
`21`		`- memoryThresholdSessionVar = "max_memory_joins"`
	`18`	`+ inMemoryJoinKey = "INMEMORY_JOINS"`
	`19`	`+ maxMemoryJoinKey = "MAX_MEMORY_INNER_JOIN"`
	`20`	`+ inMemoryJoinSessionVar = "inmemory_joins"`
	`21`	`+ memoryThresholdSessionVar = "max_memory_joins"`
`22`	`22`	`)`
`23`	`23`
`24`	`24`	`var (`
`@@ -32,7 +32,7 @@ var (`
`32`	`32`	`)`
`33`	`33`
`34`	`34`	`func shouldUseMemoryJoinsByEnv() bool {`
`35`		`- v := strings.TrimSpace(strings.ToLower(os.Getenv(experimentalInMemoryJoinKey)))`
	`35`	`+ v := strings.TrimSpace(strings.ToLower(os.Getenv(inMemoryJoinKey)))`
`36`	`36`	`return v == "on" \|\| v == "1"`
`37`	`37`	`}`
`38`	`38`
`@@ -48,7 +48,7 @@ func loadMemoryThreshold() uint64 {`
`48`	`48`	`return defaultMemoryThreshold`
`49`	`49`	`}`
`50`	`50`
`51`		`- return n`
	`51`	`+ return n * 1024 // to bytes`
`52`	`52`	`}`
`53`	`53`
`54`	`54`	`// InnerJoin is an inner join between two tables.`
`@@ -252,7 +252,7 @@ func (i *innerJoinIter) fitsInMemory() bool {`
`252`	`252`	`var maxMemory uint64`
`253`	`253`	`_, v := i.ctx.Session.Get(memoryThresholdSessionVar)`
`254`	`254`	`if n, ok := v.(int64); ok {`
`255`		`- maxMemory = uint64(n)`
	`255`	`+ maxMemory = uint64(n) * 1024 // to bytes`
`256`	`256`	`} else {`
`257`	`257`	`maxMemory = maxMemoryJoin`
`258`	`258`	`}`