After AstBuilder processing, the Unresolved LogicalPlan was obtained. There are two objects that have not been resolved in the logical operator tree: UnresolvedRelation and UnresolvedAttribute. The main role of the Analyzer is to parse these two nodes or expressions into typed objects. In this process, Catalog related information is needed. Because it inherits from the […]
Tag: logic
How to change the corresponding business logic in springboot without changing other people’s code
I think many people are like me and have the same confusion as the title. This problem has puzzled me for a long time, and now I have finally solved it. Next, let me take you through my thinking and solution process. Step one: Let’s build a simple springboot web project. pom.xml <?xml version=”1.0″ encoding=”UTF-8″?> […]
Weblogic t3 protocol analysis
Vulnerability introduction There are roughly two types of weblogic deserialization vulnerabilities, one is based on the t3 protocol and the other is based on xml Vulnerabilities based on the T3 protocol include: CVE-2015-4582, CVE-2016-0638, CVE-2016-3510, CVE-2018-2628, CVE-2020-2555, CVE-2020-2883 Among them, CVE-2020-2883 is a bypass of the CVE-2020-2555 patch, but it is actually similar. Debugging environment […]
KafkaConsumer consumption logic
Version: kafka-clients-2.0.1.jar Previously, I wanted to write a plug-in to modify the logic of the kafkaConsumer consumer and filter some messages based on headers. Therefore, we need to understand how kafkaConsumer pulls out consumption messages, and confirm whether filtering out messages before consumption will have any impact. The following is the relevant source code, explained […]
Advancement of postgresql logical replication slots
Why should the logical replication slot be advanced? We know that the logical replication slot has two functions, one is to protect the system table from being vacuumed, and the other is to protect the xlog and prevent the xlog that needs to be decoded from being recycled. If the system table does not advance […]
[PyQt] (self-made class) handles mouse click logic
I wrote a class that I think is pretty good to simplify the mouse information in mousePressEvent, mouseMoveEvent and mouseReleaseEvent. The functions include the following: Current mouse status, including left/middle/right mouse button and click/double-click/lift Mouse anti-shake (only when the mouse has moved beyond a certain level), the sensitivity can be set; Mouse long press (triggered […]
[HDLBits question] Sequential Logic — Finite State Machines (III)
(Continued from 2.5Finite State Machine(II)) 2.5.24 Q3a:FSM [Exams/2014 q3fsm] Problem description Consider a finite state machine with inputs s and w. Assume that the FSM starts from a reset state called A, as shown below, the FSM remains in state A as long as s=0, and when s=1, the A state transitions to the B […]
Weblogic CVE 2023-21839 vulnerability reappears
WebLogic has a remote code execution vulnerability (CVE-2023-21839/CNVD-2023-04389). Due to a flaw in the Weblogic IIOP/T3 protocol, when the IIOP/T3 protocol is turned on, an unauthenticated attacker is allowed to pass the IIOP/T3 protocol. Network access attacks pose security risks to WebLogic Server. If the vulnerability is successfully exploited, WebLogic Server may be taken over […]
[HDLBits question] Sequential Logic — Finite State Machines (II)
There were too many chores during the week, so I found an excuse to do some homework on the weekend. As a result, after watching the game over the weekend, the Dalian team was relegated. I was very sad and found an excuse not to do the questions. Well, it’s been a decadent week, so […]
SQL logic and optimization (must know for interviews)
What we often need to operate in development is SQL statements. SQL statements greatly determine this function. In complex businesses, there are nothing more than complex SQL statements. Like MQ and Redis, they are actually auxiliary SQL functions. So how to parse and optimize SQL? , today I will use a simple example to help […]