bytea

I've already know how to store images in DB, just use bytea type in my table And I've already can save images to DB via code in my project .net Core, I've just getting image by url and saving like there: using (HttpResponseMessage res = await client.GetAsync(photo_url)) using (HttpContent content = res.Content) { byte[] imageByte = await content.ReadAsByteArrayAsync(); using (NpgsqlConnection conn = new NpgsqlConnection("ConnectionString")) { conn.Open(); using (NpgsqlTransaction tran = conn.BeginTransaction()) using (NpgsqlCommand cmd = new NpgsqlCommand("Photo_Save", conn)) { cmd.CommandType

Hi I'm using the below code to retrieve the file from the postgresql bytea using java, but inside the file I'm getting numbers like 314530413142313141 File file = new File("c:/test.doc"); FileOutputStream fos = new FileOutputStream(file); ResultSet rs = st.executeQuery("SELECT * FROM test_bytea where id=" + 1); if (rs != null) { while (rs.next()) { byte[] fileBytes = new byte[1024]; InputStream is = rs.getBinaryStream("type_file"); while (is.read(fileBytes) > 0) { fos.write(fileBytes); } // use the stream in some way here } rs.close(); } Please let me know what goes wrong in my code? The data

For learning purposes, I'm creating a site using Python+Flask. I want to recover an image from database and show it on screen. But one step at a time. I have no idea how to save an image in my database in the first place. My searches only revealed that I have to use a bytea type in my database. Then I get my image and somehow (??) convert it to an array of bytes (bytea == array of bites?) and somehow (??) use this array in a insert command. I was able to discover (maybe) how to do it in Java ( here ) and C# ( here ), but I would really like to use Python, at least for now. Can someone help me?

I'm trying to alter a bytea column to have type oid and still retain the values. I have tried using queries like: ALTER TABLE mytable ADD COLUMN mycol_tmp oid; UPDATE mytable SET mycol_tmp = CAST(mycol as oid); ALTER TABLE mytable DROP COLUMN mycol; ALTER TABLE mytable RENAME mycol_tmp TO mycol; But that just gives me the error: ERROR: cannot cast type bytea to oid Is there any way to achieve what I want? A column of type Oid is just a reference to the binary contents which are actually stored in the system's pg_largeobject table. In terms of storage, an Oid a 4 byte integer. On the other hand

参考资料 PostgreSQL Doc: http://www.postgresql.org/docs/9.2/static/datatype-binary.html PostgreSQL public API(LargeObject): http://jdbc.postgresql.org/documentation/publicapi/index.html PostgreSQL JDBC Interface: http://jdbc.postgresql.org/documentation/head/binary-data.html 二进制类型 bytea 的操作（在最大值内，有内存限制） Create table byteatable(id int,obj bytea); ①直接强制类型输入： Insert into byteatable values(1, '123'::bytea); //插入文本 ②直接插入逃逸序列 bytea 文本逃逸八进制 http://www.postgresql.org/docs/9.2/interactive/datatype-binary.html#DATATYPE-BINARY-TABLE 十进制数值 描述 输入逃逸形式 例子 输出形式 0 八进制的零 E'\\000' SELECT E'\\000'::bytea; \000 39 单引号