bigtable/bttest: ValueFilter expression capturing additional values with alternate operator

[angelbeltran]

Client

golang Bigtable emulator, bttest

Describe Your Environment

macOS Mojave
Version 10.14.5

Inserted several rows, each with a single column with various values.
Used a ValueFilter with pattern "|a" and RowFilter to filter the rows by value.

Expected Behavior

Only rows whose column's value was "" or "a" would be retrieved.

Actual Behavior

All rows were retrieved.

Note

This behavior is not present with Bigtable, i.e. when tested against Bigtable, only rows whose column values are "" or "a" are retrieved.

[odeke-em]

Thank you for this report @angelbeltran and welcome to the Google-Cloud-Go project!

In deed, I can confirm this bug with this repro below:

package main

import (
	"context"
	"fmt"
	"log"
	"strings"

	"cloud.google.com/go/bigtable"
)

func main() {
	ctx := context.Background()
	projectID := "odeke-sandbox"
	iac, err := bigtable.NewInstanceAdminClient(ctx, projectID)
	if err != nil {
		msg := err.Error()
		switch {
		case strings.Contains(msg, "already exists"):
		case strings.Contains(msg, "unimplemented"):
		default:
			log.Fatalf("Failed to create an instance admin client: %v", err)
		}
	}
	defer iac.Close()

	instanceID := "issue-1499"
	err = iac.CreateInstance(ctx, &bigtable.InstanceConf{
		InstanceId:   instanceID,
		ClusterId:    "c1499-99",
		Zone:         "us-central1-c",
		DisplayName:  "Issue-1499 google-cloud-go",
		InstanceType: bigtable.DEVELOPMENT,
	})
	if err != nil && !strings.Contains(err.Error(), "already exists") {
		msg := err.Error()
		switch {
		case strings.Contains(msg, "already exists"):
		case strings.Contains(msg, "unimplemented"):
		default:
			log.Fatalf("Failed to create the test instance: %v", err)
		}
	}

	adminClient, err := bigtable.NewAdminClient(ctx, projectID, instanceID)
	if err != nil {
		log.Fatalf("Failed to create adminClient: %v", err)
	}
	defer adminClient.Close()

	client, err := bigtable.NewClient(ctx, projectID, instanceID)
	if err != nil {
		log.Fatalf("Failed to create NewClient: %v", err)
	}
	defer client.Close()

	tblName := "mytable"
	err = adminClient.CreateTable(ctx, tblName)
	if err != nil && !strings.Contains(err.Error(), "already exists") {
		log.Printf("Failed to create table: %v", err)
		return
	}

	columnFamilyName := "cf"
	err = adminClient.CreateColumnFamily(ctx, tblName, columnFamilyName)
	if err != nil && !strings.Contains(err.Error(), "existing") {
		log.Printf("Failed to create column family: %v", err)
		return
	}

	var muts []*bigtable.Mutation
	var rowKeys []string
	rowValues := []string{"", "a", "A", "abc"}
	for i, rowValue := range rowValues {
		mut := bigtable.NewMutation()
		mut.Set(columnFamilyName, fmt.Sprintf("col%d", i), bigtable.Now(), []byte(rowValue))
		muts = append(muts, mut)
		rowKeys = append(rowKeys, fmt.Sprintf("row%d", i))
	}

	tbl := client.Open(tblName)
	// Write the mutations.
	if _, err := tbl.ApplyBulk(ctx, rowKeys, muts); err != nil {
		log.Printf("Failed to apply mutations: %v", err)
		return
	}

	err = tbl.ReadRows(ctx, bigtable.InfiniteRange(""), func(r bigtable.Row) bool {
		log.Printf("Matched row: %#v\n", r)
		return true
	}, bigtable.RowFilter(bigtable.ValueFilter("|a")))
	log.Printf("Final error: %v\n", err)
}

Results

On Bigtable production

Matched row: bigtable.Row{"cf":[]bigtable.ReadItem{bigtable.ReadItem{Row:"row0", Column:"cf:col0", Timestamp:1563061458586000, Value:[]uint8(nil)}, bigtable.ReadItem{Row:"row0", Column:"cf:col0", Timestamp:1563060811982000, Value:[]uint8(nil)}, bigtable.ReadItem{Row:"row0", Column:"cf:col0", Timestamp:1563060541800000, Value:[]uint8(nil)}}}
Matched row: bigtable.Row{"cf":[]bigtable.ReadItem{bigtable.ReadItem{Row:"row1", Column:"cf:col1", Timestamp:1563061458586000, Value:[]uint8{0x61}}, bigtable.ReadItem{Row:"row1", Column:"cf:col1", Timestamp:1563060811982000, Value:[]uint8{0x61}}, bigtable.ReadItem{Row:"row1", Column:"cf:col1", Timestamp:1563060541800000, Value:[]uint8{0x61}}}}
Final error: <nil>

On the Bigtable emulator

$ BIGTABLE_EMULATOR_HOST=localhost:9000 go run main.go 
Matched row: bigtable.Row{"cf":[]bigtable.ReadItem{bigtable.ReadItem{Row:"row0", Column:"cf:col0", Timestamp:1563061354963000, Value:[]uint8(nil)}, bigtable.ReadItem{Row:"row0", Column:"cf:col0", Timestamp:1563061083337000, Value:[]uint8(nil)}}}
Matched row: bigtable.Row{"cf":[]bigtable.ReadItem{bigtable.ReadItem{Row:"row1", Column:"cf:col1", Timestamp:1563061354963000, Value:[]uint8{0x61}}, bigtable.ReadItem{Row:"row1", Column:"cf:col1", Timestamp:1563061083337000, Value:[]uint8{0x61}}}}
Matched row: bigtable.Row{"cf":[]bigtable.ReadItem{bigtable.ReadItem{Row:"row2", Column:"cf:col2", Timestamp:1563061354963000, Value:[]uint8{0x41}}, bigtable.ReadItem{Row:"row2", Column:"cf:col2", Timestamp:1563061083337000, Value:[]uint8{0x41}}}}
Matched row: bigtable.Row{"cf":[]bigtable.ReadItem{bigtable.ReadItem{Row:"row3", Column:"cf:col3", Timestamp:1563061354963000, Value:[]uint8{0x61, 0x62, 0x63}}, bigtable.ReadItem{Row:"row3", Column:"cf:col3", Timestamp:1563061083337000, Value:[]uint8{0x61, 0x62, 0x63}}}}
Final error: <nil>

[odeke-em]

So the problem here exists because it seems like Bigtable on production splits regex parts by the OR operator "|" if it isn't in or detectes "|" while in the Bigtable emulator we try to match the whole regex ^<PATTERN>$ and translated ^|a$ therefore matches all the values, since in re2 and PCRE, |a will also match the empty character and the same applies for Python too.

@igorbernstein2 I am going to send a CL that mimicks the functionality of Bigtable that I am deriving from the outside just by examining its responses, but please feel free to chime in.

[odeke-em]

I've mailed https://code-review.googlesource.com/c/gocloud/+/42790

[odeke-em]

From the offline discussion with @igorbernstein2, he has let me know that Bigtable's regex translation is according to this rule
ANY_USER_REGEX -> ^(?:ANY_USER_REGEX)$

and that makes the CL a whole lot simpler but also matches the cases properly.
Thank you Igor!