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Fetches all rows by default on query, like libpq. #117

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Fetches all rows by default on query, like libpq. #117

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059db7f
* Fetches all rows by default on query, like libpq. This allows multi…
RangelReale Jul 18, 2013
9f4267d
* Use slice instead of container/list
RangelReale Jul 18, 2013
b8a200f
Merge branch 'master' of https://github.com/lib/pq
RangelReale Aug 15, 2013
9447191
Revert "Use scratch buffer instead of allocating in lots of places"
RangelReale Aug 15, 2013
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81 changes: 77 additions & 4 deletions conn.go
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ package pq

import (
"bufio"
"container/list"
"crypto/md5"
"crypto/tls"
"database/sql"
Expand Down Expand Up @@ -35,9 +36,10 @@ func init() {
}

type conn struct {
c net.Conn
buf *bufio.Reader
namei int
c net.Conn
buf *bufio.Reader
namei int
singlerowmode bool
}

func Open(name string) (_ driver.Conn, err error) {
Expand Down Expand Up @@ -80,6 +82,9 @@ func Open(name string) (_ driver.Conn, err error) {
cn := &conn{c: c}
cn.ssl(o)
cn.buf = bufio.NewReader(cn.c)
if o.Get("singlerowmode") == "true" {
cn.singlerowmode = true
}
cn.startup(o)
return cn, nil
}
Expand Down Expand Up @@ -445,7 +450,15 @@ func (st *stmt) Close() (err error) {
func (st *stmt) Query(v []driver.Value) (_ driver.Rows, err error) {
defer errRecover(&err)
st.exec(v)
return &rows{st: st}, nil
r := &rows{st: st}
if st.cn.singlerowmode {
return r, nil
}

// fetch all rows
rc := &rowscomplete{}
err = rc.load(r)
return rc, err
}

func (st *stmt) Exec(v []driver.Value) (res driver.Result, err error) {
Expand Down Expand Up @@ -607,6 +620,66 @@ func (rs *rows) Next(dest []driver.Value) (err error) {
panic("not reached")
}

type rowscomplete struct {
rows *list.List
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Why not just [][]driver.Value here?

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Aren't slices costly to append? As I can't know beforehand how many records there will be.

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append behaviour is fairly reasonable, it doesn't just grow the slice by one each time you append. list.List also uses reflection, so there's a performance hit from that.

http://play.golang.org/p/SybwNAQOQ9

PASS
BenchmarkSlice1000     10000        125335 ns/op
BenchmarkSlice10000     1000       2363422 ns/op
BenchmarkSlice100000          50      28006284 ns/op
BenchmarkSlice1000000          5     273778224 ns/op
BenchmarkSlice10000000         1    3812814581 ns/op
BenchmarkList1000       5000        468516 ns/op
BenchmarkList10000       500       5936557 ns/op
BenchmarkList100000       20      70525959 ns/op
BenchmarkList1000000           5     737343756 ns/op
BenchmarkList10000000          1    8153616298 ns/op
ok      bench   31.456s

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Good to know, I updated my fork.

current *list.Element
done bool
cols []string
}

func (rs *rowscomplete) load(r *rows) (err error) {
defer r.Close()

rs.rows = list.New()
rs.cols = r.st.cols

// fetch all records
for {
dest := make([]driver.Value, len(rs.cols))
if err = r.Next(dest); err != nil {
break
}
rs.rows.PushBack(dest)
}

if err == io.EOF {
return nil
}

return
}

func (rs *rowscomplete) Close() error {
return nil
}

func (rs *rowscomplete) Columns() []string {
return rs.cols
}

func (rs *rowscomplete) Next(dest []driver.Value) (err error) {
if rs.done {
return io.EOF
}

if rs.current == nil {
rs.current = rs.rows.Front()
} else {
rs.current = rs.current.Next()
}

if rs.current == nil {
rs.done = true
return io.EOF
}

for i, v := range rs.current.Value.([]driver.Value) {
dest[i] = v
}

return nil
}

func md5s(s string) string {
h := md5.New()
h.Write([]byte(s))
Expand Down