fix: work_mem formulas based on...

.. memory percentage defined in the profile. Now each profile defines
the maximum of total memory used when computing a per connection related
buffer, like `work_mem`.

Signed-off-by: Sebastian Webber <[email protected]>

pkg/category/memory.go

@@ -1,6 +1,9 @@
 package category
 
-import "github.com/pgconfig/api/pkg/config"
+import (
+	"github.com/pgconfig/api/pkg/config"
+	"github.com/pgconfig/api/pkg/profile"
+)
 
 // MemoryCfg is the main memory category
 type MemoryCfg struct {
@@ -10,12 +13,36 @@ type MemoryCfg struct {
 	MaintenanceWorkMem config.Byte `json:"maintenance_work_mem"`
 }
 
+// Memory changes inspired by https://www.enterprisedb.com/postgres-tutorials/how-tune-postgresql-memory
+
+// MaxMemoryPercent limits the maximum memory used
+// for the profile when computing per connection buffers
+var MaxMemoryPercent = map[string]float32{
+	profile.Web:     0.25,
+	profile.OLTP:    0.35,
+	profile.DW:      0.50,
+	profile.Mixed:   0.2,
+	profile.Desktop: 0.1,
+}
+
+const (
+	// SharedBufferPerc defines the percentage of ram
+	// for the shared_buffers setting
+	SharedBufferPerc = 0.25
+
+	// EffectiveCacheSizePerc defines the percentage of ram
+	// for the effective_cache_size setting - basically the
+	// total_ram - shared_buffers
+	EffectiveCacheSizePerc = 1 - SharedBufferPerc
+)
+
 // NewMemoryCfg creates a new Memory Configuration
 func NewMemoryCfg(in config.Input) *MemoryCfg {
+
 	return &MemoryCfg{
-		SharedBuffers:      config.Byte(in.TotalRAM) / 4,
-		EffectiveCacheSize: (config.Byte(in.TotalRAM) / 4) * 3,
-		WorkMem:            in.TotalRAM / config.Byte(in.MaxConnections),
-		MaintenanceWorkMem: config.Byte(in.TotalRAM) / 16,
+		SharedBuffers:      config.Byte(float32(in.TotalRAM) * SharedBufferPerc),
+		EffectiveCacheSize: config.Byte(float32(in.TotalRAM) * EffectiveCacheSizePerc),
+		WorkMem:            config.Byte(float32(in.TotalRAM) * MaxMemoryPercent[in.Profile] / float32(in.MaxConnections)),
+		MaintenanceWorkMem: config.Byte(float32(in.TotalRAM) * 0.05),
 	}
 }