我在c＃中做了一個應用程序。它刪除重複索引根據您的優先級，希望它會幫助
它可能需要很大的改進，但我知道的是......它並不只是刪除那些涉及主要（複合）和外鍵一時間（這不應該是平時好辦法）
Here is download link for complete application with source
以下是上面的鏈接的主文件
using System;
using System.Data;
using MySql.Data.MySqlClient;
using System.Collections.Generic;
namespace duplicateIndexRemover
{
public class duplicateIndexRemover
{
static List<string> toDrop;
public string main(System.Windows.Forms.DataGridView dgv, System.Windows.Forms.DataGridView dgv1, string dbName)
{
try
{
toDrop = new List<string>();
List<table> tbs = new List<table>();
DataTable dt1 = new DataTable();
string cnStr = "SERVER=localhost;DATABASE=" + dbName + ";UID=root;";
MySqlConnection conn = new MySqlConnection(cnStr);
MySqlCommand cmd = conn.CreateCommand();
cmd.CommandText = @"SELECT Table_Name,Column_Name,Index_Name,NON_UNIQUE
FROM information_schema.STATISTICS
WHERE table_schema = '" + dbName + "' order by Table_Name,Column_Name,Index_Name";
MySqlDataAdapter adp = new MySqlDataAdapter(cmd);
DataTable dt = new DataTable();
adp.Fill(dt);
dgv.DataSource = dt;
for (int i = 0; i < dt.Columns.Count - 1; i++)
dt1.Columns.Add(dt.Columns[i].ColumnName);
table tb = new table();
column cl = new column();
index dx = new index();
tb.nam = dt.Rows[0][0].ToString();
cl = addColumn(dt, tb, 0);
tbs.Add(tb);
for (int i = 1; i < dt.Rows.Count; i++)
{
if (tb.nam != dt.Rows[i][0].ToString())
{
// 1st column of (current) t_th table
tb = new table();
tb.nam = dt.Rows[i][0].ToString();
cl = addColumn(dt, tb, i);
tbs.Add(tb);
}
else
{
if (cl.nam != dt.Rows[i][1].ToString())
cl = addColumn(dt, tb, i);
else
{
// Duplicate Indices
// But this one may be primary/unique key
// Then it would not be good to make a drop statement for this index here
// It may be improvable, but i can not apply as well condition here if it is not primary key
addIndex(dt, cl, i);
}
}
}
makeDropStatements(tbs, dt1);
dgv1.DataSource = dt1;
cmd.Connection.Open();
for (int i = 0; i < toDrop.Count; i++)
{
cmd.CommandText = toDrop[i];
try
{
cmd.ExecuteScalar();
}
catch//(Exception ex)
{
//System.Windows.Forms.MessageBox.Show("Table : " + dt1.Rows[i][0] + " Column : " + dt1.Rows[i][1] + "\n\n" + ex.Message);
}
}
cmd.CommandText = @"select table_name from information_schema.STATISTICS
WHERE table_schema = '" + dbName + "' group by table_name,column_name";
DataTable dg = new DataTable();
adp.Fill(dg);
string msg = " Total Number of Indices : " + dt.Rows.Count;
msg += "\t Droppable Indices : " + toDrop.Count;
msg += "\t Total Number of Indexed Columns : " + dg.Rows.Count;
return msg;
}
catch (Exception ex)
{
System.Windows.Forms.MessageBox.Show(ex.Message);
return ex.Message;
}
}
private static column addColumn(DataTable dt, table tb, int i)
{
column cl = new column();
// 1st index of i_th column of t_th table
cl.nam = dt.Rows[i][1].ToString();
addIndex(dt, cl, i);
tb.cols.Add(cl);
return cl;
}
private static void addIndex(DataTable dt, column cl, int i)
{
index dx = new index();
dx.nam = dt.Rows[i][2].ToString();
dx.non_unique = Convert.ToBoolean(dt.Rows[i][3]);
cl.indices.Add(dx);
}
private static void makeDropStatements(List<table> tbs, DataTable dt1)
{
bool chekd;
List<index> temp;
for (int t = 0; t < tbs.Count; t++)
{
for (int i = 0; i < tbs[t].cols.Count; i++)
{
temp = tbs[t].cols[i].indices;
if (temp.Count > 1)
{
chekd = false;
for (int j = 0; j < temp.Count; j++)
{
if (temp[j].nam == "PRIMARY")
{
getToDropIndices(tbs[t].nam, tbs[t].cols[i].nam, temp, j, dt1);
chekd = true;
break;
}
}
if (!chekd)
{
for (int j = 0; j < temp.Count; j++)
{
if (!temp[j].non_unique)
{
getToDropIndices(tbs[t].nam, tbs[t].cols[i].nam, temp, j, dt1);
chekd = true;
break;
}
}
}
if (!chekd)
{
getToDropIndices(tbs[t].nam, tbs[t].cols[i].nam, temp, 0, dt1);
chekd = true;
break;
}
}
}
}
}
private static void getToDropIndices(string tbl, string col, List<index> sublist, int nt, DataTable dt1)
{
for (int j = 0; j < nt; j++)
{
toDrop.Add("alter table `" + tbl + "` drop index " + sublist[j].nam);
dt1.Rows.Add(dt1.NewRow());
int r = dt1.Rows.Count - 1;
dt1.Rows[r][0] = tbl;
dt1.Rows[r][1] = col;
dt1.Rows[r][2] = sublist[j].nam;
}
for (int j = nt + 1; j < sublist.Count; j++)
{
toDrop.Add("alter table `" + tbl + "` drop index " + sublist[j].nam);
dt1.Rows.Add(dt1.NewRow());
int r = dt1.Rows.Count - 1;
dt1.Rows[r][0] = tbl;
dt1.Rows[r][1] = col;
dt1.Rows[r][2] = sublist[j].nam;
}
}
}
public class table
{
public List<column> cols =new List<column>();
public string nam = "";
}
public class column
{
public List<index> indices = new List<index>();
public string nam = "";
}
public class index
{
public string nam = "";
public bool non_unique;
}
}
你可以忽略/刪除GridView的它們只是展示你的指數。你只需要調用主函數
你能舉一個你正在談論的例子嗎？例如'ExampleTableName中的show index' – FoolishSeth
是的，我將更新sqlfiddle鏈接。和你說的一樣。 'show idex from'，然後在丟棄之前保存這些索引 – Sami
僅給定數據庫模式，沒有單一的「最佳索引策略」。事實上，在不知道要在數據上執行的查詢的情況下參考索引是沒有意義的。索引是一種折衷：它們減慢了寫入操作（插入/更新），但加快了讀取操作（選擇）;因此，對於您而言，「最佳」索引策略將取決於應用程序執行的讀寫比例。它還取決於實際的查詢，因爲不同的查詢將受益於不同的索引。 – eggyal